Innovations in Assessing ADHD: Development, Psychometric ......Journal of Psychopathology and Behavioral Assessment, Vol. 20, No. 4, 1998 Innovations in Assessing ADHD: Development,

Journal of Psychopathology and Behavioral Assessment, Vol. 20, No. 4, 1998

Innovations in Assessing ADHD: Development,Psychometric Properties, and Factor Structure ofthe ADHD Symptoms Rating Scale (ADHD-SRS)

Melissa Lea Holland,1 Gretchen A. Gimpel,1 and Kenneth W. Merrell2

Accepted: October 3, 1998

This research involved the development of a behavior rating scale designed tomeasure ADHD and the investigation of the scale's psychometric propertiesand factor structure. This scale, the ADHD Symptoms Rating Scale(ADHD-SRS), was developed for the assessment of ADHD in the school-age(K-12) population. Participants were 1006 children and adolescents (in gradesK-12) who were rated by their parents and/or teachers. The results indicatethat the ADHD-SRS possesses strong internal consistency reliability andtest-retest reliability and moderate cross-informant reliability. The data alsosuggest that the ADHD-SRS has strong content validity. Convergent validityof this instrument was also high, as demonstrated by correlations with threepreviously validated behavior rating scales. Significant age and genderdifferences in ADHD symptoms were found with both the parent and teacherrespondent populations. Finally, the factor analysis of the ADHD-SRSsuggested a two factor oblique rotation as the best fit for both the parent andthe teacher data. After a visual inspection of the items which loaded on eachfactor, Factor 1 was named Hyperactive-Impulsive and Factor 2 was namedInattention. These two factors, along with the items which loaded on eachfactor, appear to be remarkably similar to the two categories listed in theDSM-IV for ADHD. Directions for future research, as well as clinicalimplications and limitations of the research are discussed.

KEY WORDS: attention deficit-hyperactivity disorder (ADHD); assessment; children; adoles-cents.

1Utah State University, Logan, Utah 84322.2The University of Iowa, Iowa City, Iowa 52242.

307

0882-2689/98/1200-0307$ 15.00/0 © 1998 Plenum Publishing Corporation

INTRODUCTION

Attention deficit-hyperactivity disorder (ADHD) is one of the mostfrequent problems for which children are referred to mental health clinicsin the United States, constituting up to half of the referrals to outpatientclinics (Cohen, Becker, & Campbell, 1990; Frick & Lahey, 1991). It is es-timated that approximately 3-5% of the childhood population has ADHD(Barkley, 1990; Burnley, 1993; Fowler, 1991; McBurnett, Lahey, & Pfiffner,1993), though some studies have reported an even higher incidence (Ross& Ross, 1982; Silver, 1992; Whitman, 1991).

The Diagnostic and Statistical Manual of Mental Disorders—Fourth Edi-tion (DSM-IV) defines ADHD as "a persistent pattern of inattention and/orhyperactivity-impulsivity that is more frequent and severe than is typicallyobserved in individuals at a comparable level of development" (APA, 1994,p. 78). These two broad areas of inattention and hyperactivity-impulsivityeach consist of nine different symptoms within the DSM-IV These symptomsmust be causing impairment in at least two settings (i.e., home and school),and there must be clear evidence that the symptoms interfere with appro-priate academic, social or occupational functioning. The symptoms cannotbe better accounted for by another mental disorder (APA, 1994).

Differentiation of inattentive symptoms and hyperactive-impulsivesymptoms and the addition of four behavioral descriptors in the DSM-IVis a change from the diagnostic criteria in the DSM-III-R which did notdifferentiate between these different types of symptoms and had fewer be-havioral descriptors. This change is substantiated in the literature (Bauer-meister et al., 1995; Lahey et al., 1994; Sabatino & Vance, 1994), whichindicates that the 14 symptom ADHD syndrome in the DSM-III-R wasnot inclusive enough to explain adequately the full range of complex be-haviors that can occur in ADHD.

In addition to the primary symptomatology of inattention, impulsivityand hyperactivity, children with ADHD often experience other difficulties.One such difficulty is poor academic performance, with almost all childrenreferred for ADHD typically underachieving in relation to their known abil-ity levels (Barkley, 1990; Durbin, 1993). In addition to school performance,significant problems with oppositional and defiant behaviors, aggressive-ness, and antisocial behaviors are also very prevalent in these children, with35-60% of all ADHD clinic-referred children also meeting the criteria foroppositional defiant disorder (Barkley, 1990; Frick & Lahey, 1991) and 41-75% also meeting the criteria for conduct disorder (Frick, Strauss, Lahey,& Christ, 1993). Studies on childhood ADHD have indicated that peer re-lationship problems for children may be related to their inattentive, dis-ruptive socially immature and provocative behaviors (Barkley, 1990; Frick

308 Holland, Gimpel, and Merrell

& Lahey, 1991). Research has also found that these children tend to elicitnegative interactions with their parents and teachers as a result of theirbehavior (Guevremont & Barkley, 1992). Poor self-esteem and emotionaldisorders may emerge as a result of chronic failure and conflict in familyand social functioning (Frick & Lahey, 1991).

These primary and secondary symptoms of ADHD appear to affectboth males and females. However, boys are approximately three times morelikely to be diagnosed with ADHD than girls (Barkley, 1990; Brown,Madan-Swain, & Baldwin, 1991). In clinic referred populations, the male-to-female ratio rises to 9:1, respectively, indicating that boys with ADHDare far more likely to be referred to clinics for evaluation and treatmentthan girls (APA, 1994; Barkley, 1996). Few studies have investigated genderdifferences in childhood ADHD symptomatology. In a study conducted byBrown et al. (1991), it was found that girls with ADHD were retained inschool more frequently than boys, were more underidentified than boys,and were less aggressive than their ADHD male counterparts. Few genderdifferences, however, were obtained on measures of concentration and at-tention, intellectual functioning, academic achievement, distractibility, par-ent and teacher ratings of internalizing and externalizing behavioralsymptoms, and social competence (Brown et al., 1991). Silverthorn, Frick,Kuper, and Ott (1996) also found no differences across gender on measuresof neurological and cognitive status. In a study of situational variability con-ducted by Breen and Altepeter (1990), no clear gender differences werefound in children identified as ADHD. Barkley (1990) noted that, in gen-eral, girls may have fewer conduct problems and may be less aggressivethan boys, but otherwise appear to be little different in their pattern ofADHD symptoms. More research should be conducted in order to definemore clearly the differences that exist, if any, between male and femaleADHD symptomatology (Faraone, Biederman, Keenan, & Tsuang, 1991).

Much of the literature indicates that ADHD symptomatology changesas children with ADHD progress in age (Barkley, 1990, 1996; Sleator, 1986;Wender, 1987). The symptoms of ADHD often first appear in the preschoolyears (Barkley, 1996). Children with ADHD at this age level are describedby parents as always on the go, restless, acting as if driven by a motor, andfrequently getting into or climbing on things. These children often haveinjuries as a result of these overactive and impulsive behaviors (Barkley,1990). Preschoolers with ADHD are also characterized as having a shortattention span, being unable to pay attention to activities for any lengthof time (Wender, 1987), and being talkative and noisy (Barkley, 1996).

The hyperactive and impulsive behaviors of the preschool years persistas the child with ADHD enters elementary school. Elementary-age childrenwith ADHD often are restless in their seats, fidgeting and squirming during

The ADHD Symptoms Rating Scale 309

school or home work time (Wender, 1987). These children also begin tohave difficulties with sustained attention, including forgetfulness and dis-tractibility (Barkley, 1996). With the increased amount of homework andschool supplies to keep track of, elementary age children with ADHD oftenare disorganized and do not follow through on many tasks and activities.It is often during this time that the child with ADHD also begins to ex-perience social rejection from both peers and adults (Barkley, 1990).

In adolescence there is often a decline in ADHD symptomatology asreported on behavior rating scales. However, simply because the severitylevels of symptoms may decline with age does not necessarily mean thatchildren with ADHD are outgrowing their disorder (Barkley, 1996). In-stead, it is estimated that approximately 50-80% of all clinic-referred chil-dren for ADHD will continue to have ADHD symptomatology into theirteenage years (Barkley, Fischer, Edelbrock, & Smallish, 1990), and 30-50%of children with ADHD continue to exhibit ADHD symptoms in adulthood(Silver, 1992; Weiss & Hechtman, 1986). As children mature, the symptomsof ADHD usually become less conspicuous. For example, signs of excessivegross motor activity (excessive climbing or running) may be confined in-stead to feelings of inner restlessness or fidgetiness (APA, 1994). It isthought that adolescents and adults with ADHD may develop adaptiveskills to cope with ADHD symptomatology but that they may still face thesame core symptoms of inattention, hyperactivity, and impulsivity.

One of the first steps in helping children who exhibit ADHD sympto-matology is to conduct an assessment to detect if the child does have ADHD(Durbin, 1993). Unfortunately, there is no simple test that can detectwhether the child has this disorder (Fowler, 1991). A diagnosis of ADHDis typically made by a clinician after comparing the results of various assess-ment measures against the definitional criteria for the disorder. The mostfrequently used assessment methods for the identification of ADHD in chil-dren are attentional and cognitive tasks, interviews, observational methods,and rating scales (Barkley, 1990; Guevremont & Barkley, 1992).

Rating scales offer numerous advantages over the other assessmentmethods (Barkley, 1990; Sleator, 1986). For example, rating scales permitdata collection of infrequent behaviors that are likely to be missed by ob-servations (Barkley, 1990), and they can be used to gather information fromthose who have been responsible for the care and management of the childacross different situations and settings (Barkley, 1990; Blondis, Snow, Stein,& Roizen, 1991). They are also relatively easy to administer and inexpen-sive (Ross & Ross, 1982). Rating scales often have normative data availablefor establishing the statistical significance of the child's behaviors (Guevre-mont & Barkley, 1992; Guevremont, DuPaul, & Barkley, 1993), and theypermit the quantification of qualitative aspects of behavior which are often


difficult or impossible to obtain through interviews, cognitive tasks, or directobservation (Barkley, 1990; Sleator, 1986).

Although rating scales offer numerous advantages, many of the currentlyexisting scales are not adequate for assessing ADHD (Reid, Maag, & Vasa,1993). Some of them were developed before the publication date of theDSM-IV, and therefore are not based on the current criteria most commonlyused for the diagnosis of ADHD in children. Many of the rating scales haveunreported or inadequate reliability and validity (Reid et al., 1993). Some ofthe rating scales focus on other disorders along with ADHD, which may notgenerate an in-depth and complete assessment of ADHD. Although somenew scales have been developed based on the DSM-IV criteria, these scalesvary in how long or thorough they are, and each scale is bound to have itsown "instrument variance." Instrument variance entails the phenomenon ofdifferent rating scales often measuring related, but slightly different con-structs, and, as a result, a severe behavior problem score on one rating scalemay be equivalent to only a moderate behavior problem score on anotherscale. Also, if the normative populations for scoring comparisons are not rep-resentative of the population as a whole or not randomly selected, similarresults on two different rating instruments may not mean the same thing.One way to control for instrument variance is by using the aggregation prin-ciple, in which more than one type of rating scale is used for assessing prob-lem behaviors. The use of this principle helps to reduce response bias andvariance problems in the assessment through obtaining rating evaluationsfrom different sources and by using more than one type of rating scale inthe assessment (Merrell, 1994). For this reason it is good for researchers andpractitioners to have several instruments to choose among. Therefore, thereis still a need for additional assessment instruments to be developed.

The ADHD Symptoms Rating Scale (ADHD-SRS) is a new researchinstrument designed to assess the symptoms of attention deficit-hyperac-tivity disorder in the K-12 school age population. The ADHD-SRS offersnumerous advantages over other currently existing ADHD behavior ratingscales. The purpose of this article is to detail the development of theADHD-SRS and to present research evidence regarding its psychometricproperties and factor structure.

METHOD

Instrument Development

The initial development of the items for the ADHD-SRS utilized a ra-tional-theoretical approach to test construction (Lanyon & Goldstein, 1982).


A thorough review of the literature on ADHD in children and adolescentswas conducted to facilitate the selection of potential items to represent thetwo DSM-IV domains of ADHD: inattention and hyperactivity-impulsivity.Eighty-one symptom descriptors were developed through this search. Thesedescriptors were reviewed and corresponding items were developed. Somedescriptors were eliminated due to redundancy, improper fit with the DSM-IV ADHD categories, and vagueness or complexity of the descriptor. Sixty-one potential items remained after this process.

Content validation was conducted on the 61 potential items. Thirty-fiveexpert judges in ADHD (e.g., child clinical psychologists, university profes-sors, school psychologists, pediatricians) from 10 U.S. states were asked torate the 61 items on a 3-point scale (2 = definitely appropriate, 1 = bor-derline appropriate, and 0 = inappropriate for inclusion) for (a) repre-sentation of construct, (b) appearance of gender or culture bias, and (c)appropriateness for parent and teacher judgment. Items that received lessthan a borderline appropriate rating were removed from the item pool,and several items were revised on the basis of qualitative feedback. Thisprocess resulted in 56 final items, with two to five items remaining for eachof the 18 specific ADHD symptoms listed in the DSM-IV

In addition to validity, it is also important that a measure be usable(Worthen, Borg, & White, 1993). The overall usability and item quality ofthe ADHD-SRS items were rated on a 5-point scale (i.e., 1 = "poor" to5 = "excellent") by both a parent (n = 36) and a teacher (n = 21) panel.The overall usability of the scale was rated as being between adequate andexcellent (mean = 4.42), and the overall quality of the items as being be-tween adequate and excellent (mean = 4.19). Through the ratings of thecontent validation panel and the parent and teacher panels, a frequencyof behavior rating format ("behavior does not occur" to "behavior occursone to several times an hour") was found to be the desired rating scaleformat over a traditional rating scale format ("behavior never occurs" to"behavior often or to a great degree occurs). This final version of the scalewas used in all following research.

Subjects

The preliminary normative sample for this research included 1006 chil-dren and adolescents in grades K-12 who were rated by their parentsand/or teachers. A grade by gender breakdown of the subjects is presentedin Table I. The sections which follow more closely examine the charac-teristics of this sample.


The ADHD Symptoms Rating Scale

Geography. The subjects were obtained from six public school districtsin the United States. These participating school districts were from fiveU.S. states with the following breakdown of subjects: California, 21.6%;Idaho, 7.8%; Kentucky, 14.0%; Ohio, 27.7%; and Utah, 28.9%. The sixparticipating school districts were a mix of urban, suburban, small town,and rural communities.

Race/Ethnicity. The racial/ethnic makeup of the ADHD-SRS prelimi-nary normative sample was as follows: 88.4% Caucasian, 3.2% AfricanAmerican, 2.9% Hispanic, 2.8% Asian or Pacific Islander, and 0.4% de-scribed as "other." Approximately 2.4% of the sample did not respond tothis question. The percentage of ethnic/racial minorities in the norm groupwas only 9.3%, compared with 30.8% of the general U.S. population, in-dicating that the non-white population was underrepresented in this sample(U.S. Bureau of the Census, 1990).

Special Education/Previous ADHD Diagnosis. Of the 1006 children andadolescents in the preliminary normative sample, 90% were not receivingspecial education services and 9.2% did receive services (0.8% were un-known). This percentage approximates the estimated 12% of students na-tionally who receive special education services (U.S. Department ofEducation, 1995). In terms of specific special education service categories,2.3% were classified as Learning Disabled, 2.1% were classified as SpeechLanguage Disordered or Communication Disordered, 0.6% were classifiedas Mentally Retarded or Intellectually Disabled, 0.6% were classified as

313

Table I. Grade by Gender Breakdown for theSubjects (N = 1006)

Gender

Grade

K123456789

101112

Total

Male

728677883628212868

271615

508

Female

66756971433326346

16261813

496

Total

138161146159796147621224533428

1004a

aMissing = 2.

Emotionally or Behaviorally Disturbed, and 3.5% were identified as havingother disability conditions.

With regard to a previous diagnosis of ADHD, 83.2% of the prelimi-nary normative group had never been diagnosed with ADHD, while 6.4%had been previously diagnosed with ADHD (for 10.4% of the sample thisinformation was unknown). This approximates the prevalence rate ofADHD in the general population.

Data Collection Procedures

Data were collected with the assistance of coordinators working in publicschools (school psychologists and teachers). Following district approval, coor-dinators distributed to teachers three ADHD-SRS protocols with an instruc-tional sheet. Teachers were asked to complete the rating scales on the firstthree students on their class role and then return the completed protocols tothe coordinator, who returned them to the investigators. Participating teacherswere also asked to send home a packet with each child in their class containingrating scales for the parents to complete. A business-reply envelope was en-closed so that parents mailed their scales directly back to the authors.

Children's names were not put on the scales. Identification numberswere assigned to the scales and the teachers were asked to match the num-bers on the scales they completed to the scales the parents received sothat for those children on whom both a parent and a teacher completeda scale, the results could be matched. Instructions at the top of the ADHD-SRS directed participants to complete an informational section providedin the packet about their child or student (i.e., age, sex, grade, if the childis receiving special education services, if the child has been diagnosed withADHD, etc.) and to complete the ADHD-SRS carefully, without skippingany items, and deciding how often the child being rated has demonstratedthe behaviors in the past 3 months.

Convergent Validity Measures

During the collection of data from the preliminary normative group, sev-eral other ADHD behavioral rating scales were also administered to sub-groups of the normative population to obtain information on the convergentconstruct validity of the instrument. These measures are described as follows:

ADDES. The Attention Deficit Disorders Evaluation Scale (ADDES)is a behavior rating instrument based on the DSM-IV criteria designed toassess ADHD symptoms in the child and adolescent populations. The AD-DES has two subscales, Inattentive and Hyperactive-Impulsive. Two ver-


sions of this rating scale exist: a home version (46 items) and a schoolversion (60 items). The school version was normed on a total of 5795American students ages 4-19, and the home version was normed on a totalof 2415 children and youth ages 3-29. Adequate psychometric propertiesare reported for the scale in the ADDES manuals (McCarney, 1995).

CTRS-39. The Conners' Teacher Rating Scale (CTRS-39) is a 39-itembehavior rating instrument. The CTRS-39 rating format involves respond-ing with one of the following four responses to the items: not at all, just alittle, pretty much, or very much. This rating scale has six subscales, includingHyperactivity, Conduct Problem, Emotional-Overindulgent, Anxious-Pas-sive, Asocial, and Daydream-/Attention Problem. In addition, the scale con-tains a Hyperactivity Index, a collection of 10 items from the otherCTRS-39 subscales that were found to be especially sensitive to pharma-cological treatment effects with ADHD children. The CTRS-39 wasnormed on over 9,500 Canadian children. Separate norms are available forboth age and gender. Adequate psychometric properties are reported forthe scale in the CTRS-39 manual (Conners, 1990).

AD/HD Rating Scale-IV The AD/HD Rating Scale-IV is an 18-itembehavior rating scale based on the DSM-IV criteria for ADHD. This scale,developed by DuPaul, Anastopoulos, Power, Murphy, and Barkley (1996)includes both home and school versions. The AD/HD Rating Scale-IV con-tains two subscales, the Inattention Scale and the Hyperactivity-ImpulsivityScale, which are summed to calculate the Total Score of the items. Nor-mative data are available for children and adolescents between 5 and 18years old (kindergarten through 12th grade) and were obtained from over2000 teachers and 4500 parents in a national sample. The normative groupreportedly closely matched the 1990 U.S. Census data for distributionacross regions and ethnic groups. Adequate test-retest reliability (>.75 for4-week interval) and internal consistency (>.80) has been reported by theauthors. Scores of both the home and school version correlate significantlywith the Conners' Parent and Teacher Rating Scales, and confirmatory fac-tor analyses support the two-factor model that conforms to the DSM-IVbreakdown of symptoms (DuPaul et al., 1996).

RESULTS

Factor Structure

Exploratory factor analyses of the ADHD-SRS were conducted sepa-rately for both the parent and teacher ratings. These analyses are discussedbelow.


Parent Ratings. A total of 650 parent ratings were collected. Protocolsmissing item responses were excluded from the analyses, resulting in a totalof 559 parent ratings used in the parent factor analyses. There appearedto be no particular pattern or trend regarding which responses were missingon these protocols. This sample size exceeds the 4:1 or 5:1 (subjects tovariables) ratio recommended for exploratory factor analysis (Floyd & Wi-daman, 1995). One common guideline regarding the number of factors isto extract factors with eigenvalues greater than 1.00 (Tabachnik & Fidell,1989). Using this guideline, a maximum of five factors would be retained.

Numerous exploratory principal component factor analyses were con-ducted, using both orthogonal and oblique rotations and retaining betweenone and five factors. A principal-component two factor-specified directoblique rotation resulted in the fewest double loadings and appeared tobe the most clinically interpretable. This two-factor solution resulted in onlyfive double loadings. The first factor, consisting of 34 items, accounted for29.9% of the variance (eigenvalue = 29.29). This factor was labeled Hy-peractive-Impulsive, as it consisted primarily of items related to hyperactivityand impulsivity (e.g., "restless or overactive," "makes excessive noise,""blurts out," "has difficulty waiting turn in line"). The second factor, con-sisting of 27 items, accounted for 27.9% of the variance (eigenvalue =3.12). This factor was labeled Inattention, as it consisted primarily of itemsrelated to being inattentive (e.g., "is disorganized with school work orhomework assignments," "is forgetful (forgets things)," "has difficulty re-maining on task," "does not organize activities"). The factor structure ofthis rotation is presented in Table II. The correlation between the two fac-tors was .69.

Teacher Ratings. A total of 432 teacher ratings were collected. Again,protocols missing item responses were excluded from the analyses, resultingin a total of 392 teacher ratings used in the teacher sample factor analyses.There appeared to be no particular pattern or trend regarding which re-sponses were missing on thee protocols. This sample size also exceeds the4:1 or 5:1 (subjects to variables) minimum ratio. Principal-component factoranalyses with both orthogonal and oblique rotations were conducted.Again, initially only factor with eigenvalues greater than 1.00 were extracted(Tabachnik & Fidell, 1989).

As in the analyses of parent ratings, item-level data for the 392 teacherratings were subjected to both orthogonal and oblique rotation methods,with a range of one to five factors specified. A principal component twofactor specified direct oblique rotation resulted in the fewest double load-ings and appeared to be the most clinically interpretable. This two-factorsolution resulted in only four double loadings. The first factor, consistingof 35 items, accounted for 38.3% of the variance (eigenvalue = 35.91).



Table II. Two-Factor Oblique Rotation Factor Structure for

Item

1) Has a short attention span2) Talks too much3) Loses things that he/she needs4) Needs to have questions and directions repeated5) Has difficulty delaying gratification6) Fidgets and squirms7) Gets "out of control" when playing8) Makes excessive noise9) Bothers others when they are trying to work or play

10) Unable to tolerate delays11) Becomes overexcited12) Blurts out13) Rushes through chores or tasks14) Does not hear all of what has been said15) Has difficulty sitting appropriately on furniture16) Does not prepare for school assignments17) Rocks in seat18) Has difficulty waiting in turn in line19) Restless or overactive20) Has difficulty following rules of games or activities21) Shifts from one activity to another22) Does not follow the necessary steps in order to complete things23) Makes odd or annoying noises24) Produces messy or sloppy school work25) Has difficulty sustaining play activities26) Does not organize activities27) Leaves seat without permission28) Does not finish projects that he/she has started29) Has difficulty remaining on task30) Make careless mistakes31) Runs in the halls/Runs in the house32) Does not follow directions33) Interferes with other's activities34) Is easily distracted35) Asks irrelevant questions36) Does not seem to listen to what others are saying37) Dislikes doing things that require sustained mental effort38) Is forgetful (forgets things)39) Interrupts others when they are talking40) Calls out answers before the question is finished41) Has difficulty taking turns42) Has difficulty remaining seated43) Is inattentive44) Talks at inappropriate times45) Acts as if "driven by a motor"46) Gives up easily47) Has difficulty concentrating48) Always "on the go"49) Cannot find things that he/she needs50) Moves about unnecessarily

Parent Ratings

Factor 1 Factor 2

.59

.41

.71

.69

.79

.62

.52

.69

.70

.54

.66

.71

.80

.40

.48

.58

.55

.63

.59

.52

.66

.68

.72

.35

.72

.80

.70

.75

.54

.62

.66

.44

.62

.80

.43

.37

.63

.70

.43

.77

.71

.72

.72

.62

.61

.38

.52

.81

.79

.54

.67

.74

.65

Table II. Continued

Item

51) Has difficulty playing or working quietly52) Moves about while seated53) Fails to complete school work or homework54) Shifts position in seat55) Is disorganized with school work or homework56) Climbs on things

Percentage of varianceCorrelation between 2 factors = .69

Factor 1

.67

.78

.68

.69

29.9

Note. Factor loadings of less than .30 are left blank.

Factor 2

.81

.90

27.9


This factor was labeled Hyperactive-Impulsive, as it consisted primarily ofitems relating to hyperactivity and impulsivity (e.g., "acts as if driven by amotor," "becomes overexcited," "blurts out," "has difficulty waiting turn inline"). The second factor, consisting of 25 items, accounted for 31.8% ofthe variance (eigenvalue = 3.70). This factor was labeled Inattention, as itconsisted primarily of items related to being inattentive (e.g., "fails to com-plete school work or homework," "has a short attention span," "has diffi-culty remaining on task," "is inattentive"). The factor structure of thisrotation is presented in Table III. The correlation between the two factorswas .69, and the overall factor structure was virtually identical to the struc-ture obtained with parent ratings.

Reliability

Reliability is defined as the stability or consistency of an instrument(Borg & Gall, 1989). Internal consistency and temporal stability are thetwo primary types of reliability which are extensively discussed in the lit-erature (Cronbach, 1990). These different forms of test reliability for theADHD-SRS, along with cross-informant information, are presented in thissection.

Internal Consistency. Internal consistency reliability was assessed bycomputing Cronbach's coefficient alpha for the ADHD-SRS total score(i.e., the sum of all items) for the 650 parent ratings and 432 teacher rat-ings. The obtained coefficient for the parent data was .98, and the coeffi-cient alpha for the teacher data was .99. These coefficients are exceptionallystrong.

Test-Retest. The temporal stability (test-retest reliability) of theADHD-SRS was calculated using ratings from teachers of 78 elementary


Table III. Two-Factor Oblique Rotation Factor Structure for Teacher Ratings

Item

1) Has a short attention span2) Talks too much3) Loses things that he/she needs4) Needs to have questions and directions repeated5) Has difficulty delaying gratification6) Fidgets and squirms7) Gets "out of control" when playing8) Makes excessive noise9) Bothers others when they are trying to work or play

10) Unable to tolerate delays11) Becomes overexcited12) Blurts out13) Rushes through chores or tasks14) Does not hear all of what has been said15) Has difficulty sitting appropriately on furniture16) Does not prepare for school assignments17) Rocks in seat18) Has difficulty waiting in turn in line19) Restless or overactive20) Has difficulty following rules of games or activities21) Shifts from one activity to another22) Does not follow the necessary steps in order to complete things23) Makes odd or annoying noises24) Produces messy or sloppy school work25) Has difficulty sustaining play activities26) Does not organize activities27) Leaves seat without permission28) Does not finish projects that he/she has started29) Has difficulty remaining on task30) Make careless mistakes31) Runs in the halls/Runs in the house32) Does not follow directions33) Interferes with other's activities34) Is easily distracted35) Asks irrelevant questions36) Does not seem to listen to what others are saying37) Dislikes doing things that require sustained mental effort38) Is forgetful (forgets things)39) Interrupts others when they are talking40) Calls out answers before the question is finished41) Has difficulty taking turns42) Has difficulty remaining seated43) Is inattentive44) Talks at inappropriate times45) Acts as if "driven by a motor"46) Gives up easily47) Has difficulty concentrating48) Always "on the go"49) Cannot find things that he/she needs50) Moves about unnecessarily

Factor 1

.53

.67

.65

.85

.72

.63

.76

.85

.84

.60

.75

.75

.89

.83

.68

.60

.61

.37

.63

.63

.79

.59

.52

.70

.87

.78

.77

.59

.94

.85

.69

Factor 2

.73

.71

.75

.70

.84

.30

.72

.50

.63

.88

.87

.67

.71

.36

.69

.65

.79

.75

.77

.31

.71

.82

.69

Table HI. Continued

Item

51) Has difficulty playing or working quietly52) Moves about while seated53) Fails to complete school work or homework54) Shifts position in seat55) Is disorganized with school work or homework56) Climbs on things

Percentage of varianceCorrelation between 2 factors = .69

Factor 1

.71

.72

.74

.77

38.3

Note. Factor loadings of less than .30 are left blank.

Factor 2

.98

.91

31.8


and middle school students in the ADHD-SRS preliminary normative sam-ple. Teachers completed ratings of the students at a 2-week time interval.Pearson product-moment correlations between the scores of the two ad-ministrations of the ADHD-SRS were calculated. The resulting coefficientsfor the ADHD-SRS were as follows: .96 for the Hyperactive-Impulsivesubscale, .95 for the Inattention subscale, and .97 for the total score. Thesecoefficients are exceptionally high in magnitude, and are equal to or higherthan stability coefficients reported for other ADHD rating scales. For ex-ample, at 1-month test-retest intervals, the Attention Deficit DisordersEvaluation Scale (ADDES; McCarney, 1995a, b) coefficients ranged be-tween .88 and .91 for the home version and .90 and .94 for the schoolversion, and for the Conners' Teacher Rating Scale (Conners, 1990) coef-ficients ranged between .72 and .91 for a 30-day test-retest interval. Theseresults show that the ADHD-SRS provides stable ratings over short timeintervals and that ADHD behavioral characteristics are generally stableacross short time intervals.

Cross-Informant. A sample size of 76 children and adolescents was util-ized to calculate the cross-informant correspondence for the ADHD-SRS.A Pearson product-moment correlation was calculated between the parentand teacher ratings, resulting in a correlation of .26 (p = .02). This corre-lation approximates the average correlation of .28 obtained in most studiesfor cross-informant ratings (Achenbach, McConaughy, & Howell, 1987).

Validity

In the jointly produced Standards for Educational and PsychologicalTesting (APA, 1985), it is stated that "validity is the most important con-sideration in test evaluation" (p. 9). Validity refers to the extent of how

well an instrument measures what it is purported to measure (Anastasi,1988). Content validity for the ADHD-SRS was previously discussed underInstrument Development. This section explores the face and convergentvalidity of the ADHD-SRS.

Face. Face validity is the degree to which an instrument appears to meas-ure what it purports to measure (Borg & Gall, 1989). The two-factor structureobtained for the ADHD-SRS is remarkably similar to the DSM-IV categoriesfor ADHD. An objective visual inspection of the items which loaded on eachfactor and their relationship to the DSM-IV categories was conducted. Be-cause the DSM-IV categories for ADHD were originally used as a guidelinefor the ADHD-SRS item inclusion, each item on the ADHD-SRS had pre-viously been categorized into one of the two DSM-IV ADHD categories.

In examining face validity, if the items which loaded on each factorappeared to be directly related to the corresponding DSM-IV category (i.e.,"is inattentive" is related to the DSM-IV category of inattention, but "fidg-ets and squirms" is related to the category of hyperactivity-impulsivity), thenthat item was counted as being directly related to the corresponding DSM-IV category. Percentages of these corresponding items were calculated foreach factor for both the parent and the teacher data.

The majority of the items which loaded on each factor were directlyrelated to the corresponding DSM-IV category (i.e., the items which loadedon the Hyperactive-Impulsive Factor represent primarily the DSM-IVADHD category of hyperactivity-impulsivity, not the category of inattention).For the parent ratings, 93% of the items that loaded on Factor 1 (Hyper-active-Impulsive) were directly related to the DSM-IV category of hyper-activity-impulsivity. For Factor 2 (Inattention), 98% of the items weredirectly related to the DSM-IV category of inattention. For the teacher rat-ings, 91% of the items that loaded on Factor 1 (Hyperactive-Impulsive)were directly related to the corresponding DSM-IV category of hyperactiv-ity-impulsivity, and on Factor 2 (Inattention), 96% of the items were directlyrelated to the DSM-IV category of inattention. It is important to note thatalmost all of the ADHD-SRS items which did not correspond to the ap-propriate DSM-IV ADHD category for each factor were double loadings(i.e., they loaded on both Factor 1 and Factor 2). The majority of thesedouble-loaded items loaded higher on the factor with which they appearedto belong [i.e., "Is Inattentive" on the parent ratings rotation loaded at .54on Factor 2 (Inattention), while it loaded at only .35 on factor 1 (Hyper-active-Impulsive)] .

Convergent. The convergent validity of the ADHD-SRS was investigatedby calculating Pearson product-moment correlation coefficients between theADHD-SRS subscales (Hyperactive-Impulsive and Inattention) and totalscore and (a) the Attention Deficit Disorders Evaluation Scale (ADDES),


home and school versions; (b) the Conners' Teacher Rating Scale (CTRS-39); and (c) the ADH/HD Rating Scale-IV, home and school versions.

ADDES. The ADDES's two subscales (Inattention and Hyperactive-Impulsive) and total score were correlated with the two subscales and totalscore of the ADHD-SRS. The sample for these analyses included ratingsof 124 children and adolescents (96 subjects rated by teachers and 28 sub-jects rated by parents). Separate analyses were conducted for both parentand teacher ratings. The resulting correlations are displayed in Table IV

For the teacher-rated subjects, all correlations between the ADDESand the ADHD-SRS were above .80. For the parent-rated subjects, all ob-tained correlations were above .84.

CTRS-39. The sample for the correlational comparison between theCTRS-39 and the ADHD-SRS included teacher ratings of 63 children.Data were obtained for grades K-3 only. The CTRS-39's six subscales, Hy-peractivity Index, and total score were correlated with the two subscalesand total score of the ADHD-SRS. Resulting correlations are displayed inTable V

The Conduct Problem, Emotional-Indulgent, Asocial, and Daydream-Attention Problem subscales on the CTRS-39 all correlated at or above.71 with the ADHD-SRS total score. The Hyperactivity subscale and Hy-peractivity Index on the CTRS-39 were found to correlate highly with theADHD-SRS's Hyperactive-Impulsive subscale, Inattention subscale, and to-tal score. The Inattention subscale on the ADHD-SRS is thought to havecorrelated highly with the Hyperactivity subscale and the Hyperactivity In-dex on the CTRS-39 because the Hyperactivity subscale and the Hyperac-tivity Index also measure some inattentive behaviors (i.e.,


Table IV. Correlations Between the ADHD-SRS Subscales and Total Score and theAttention Deficits Disorder Evaluation Scale (ADDES), Home and School Versions

ADHD-SRS

Scale

ADDES (school)Inattentive scaleHyperactive-Impulsive scaleADDES total score

ADDES (home)Inattentive scaleHyperactive-Impulsive scaleADDES total score

Hyperactive-Impulsivesubscale

.80

.94

.91

.84

.94

.91

Inattentionsubscale Total score

.93

.88

.94

.92

.91

.94

.87

.94

.95

.88

.94

.94

Note. All correlations are significant at p < .001.

The ADHD Symptoms Rating Scale

aInattentive-Easily Distracted," "Fails to Finish Things S/he Starts-ShortAttention Span"). The Anxious-Passive subscale, however, only had a weakcorrelation with the ADHD-SRS total scores (.30) and subscales (.35 forthe Hyperactive-Impulsive subscale and .24 for the Inattention subscale).This finding is to be expected as the Anxious-Passive subscale clearly ap-pears to be measuring a different construct (i.e., leadership skills and sub-missiveness) than the ADHD-SRS. These low correlations actually provideevidence of the discriminant construct validity of the ADHD-SRS.

AD/HD Rating Scale-IV. The sample for the correlational comparisonof the AD/HD Rating Scale-IV, home and school versions, and the ADHD-SRS included ratings of 129 children and adolescents (43 subjects rated byparents and 89 subjects rated by teachers). Separate analyses were con-ducted for both parent and teacher ratings. The AD/HD Rating Scale-IV'stwo subscales (Inattention and Hyperactivity-Impulsivity) and total scorewere correlated with the subscales and total score of the ADHD-SRS. Re-sulting correlations are displayed in Table VI.

For the parent-rated subjects, the AD/HD Rating Scale-IV's subscalesand total score were found to correlate at or above .86 with the ADHD-SRS total score. The ADHD-SRS Inattention subscale correlated at .89with the AD/HD Rating Scale-IV Inattention Scale, while the ADHD-SRSHyperactive-Impulsive subscale and the Hyperactivity-Impulsivity Scale onthe AD/HD Rating Scale-IV correlated at .90.

For the teacher-rated subjects, the AD/HD Rating Scale-IV's subscalesand total score were found to correlate at or above .84 with the ADHD-SRS total score. The ADHD-SRS Inattention subscale correlated at .94with the AD/HD Rating Scale-IV Inattention Scale, while the ADHD-SRS

323

Table V. Correlations Between the ADHD-SRS Subscales and Total Score and theConners' Teacher Rating Scale (CTRS-39)

ADHD=SRS

CTRS-39 scale

HyperactiviryConduct ProblemsEmotional-IndulgentAnxious-PassiveAsocialDaydream-AttentionHyperactivity IndexTotal score


.9686.75.24.78

Problem .64.96.92

Inattentionsubscale

.94

.74

.68

.35

.74

.75

.94

.89

Total score

.97

.83

.74

.30

.78

.71

.97

.93

Note. AH correlations are significant at p < .001.

Table VI. Correlations Between the ADHD-SRS Subscales and Total Score and theAD/HD Rating Scale-IV, Home and School Versions

ADHD-SRS

Scale

AD/HD Rating Scale-IV (home)Inattention scaleHyperactivity-Impulsivity scaleAD/HD Rating Scale-IV total score

AD/HD Rating Scale-IV (school)Inattention scaleHyperactivity-Impulsivity scaleAD/HD Rating Scale-IV total score


.84

.90

.91

.65

.93

.86

Inattentionsubscale

.89

.75

.86

.94

.70

.91

Total score

.89

.86

.91

.84

.88

.94

Note. All correlations are significant at p < .001.


Hyperactive-Impulsive subscale and the Hyperactivity-Impulsivity Scale onthe AD/HD Rating Scale-IV correlated at .93.

Gender Differences

To determine if significant gender differences were present for parentand teacher ratings of children on the ADHD-SRS, t-tests and effect sizeestimates were calculated. As shown in Table VII, parents' ratings of sub-jects on the ADHD-SRS were significantly different for male and femalesubjects, with male subjects obtaining a higher mean rating on the ADHD-SRS than female subjects. Teachers' ratings were also significantly differentfor male and female subjects. Again, male subjects obtained a higher meanrating than did female subjects for teacher ratings on the ADHD-SRS.

Effect size estimates were calculated between the male and female sam-ples for both parent and teacher ratings to help determine the practical mean-ing of the score differences. This procedure was done by using the standardprocedure of dividing the difference in group means by the pooled standarddeviation for both groups (Cohen, 1988). Results are shown in Table VII.For the parent ratings, males were rated approximately one-third of a stand-ard deviation higher on the ADHD-SRS than were females (ES = .28). Forthe teacher ratings, males were rated more than one-half of a standard de-viation higher than were females (ES = .50). According to Cohen's (1988)paradigm for effect size power analysis, the parent ratings effect size differ-ence is considered to be of a significant but small magnitude, whereas the teacherratings effect size difference is considered to be of a medium magnitude.

Table VII. t-Tests and Effect Size Correlations Between Teacher- andParent-Rated Male and Female Subjects

Males

Rater

ParentTeacher

M

48.4155.03

SD

40.5357.66

Females

M

37.5030.29

SD

36.5741.07

t

3.605.16

df

643.4401.7

P

.001

.001

ES

.28

.50


Relationship of Age on ADHD-SRS Ratings)

To determine the effect of children's ages on the ADHD-SRS ratings,Pearson bivariate correlations were computed between the ages of the sub-jects and the total scores they received by parents and teachers. The re-sulting correlation coefficient for both the parent and the teacher ratingswas -.20 (p < .0010). These results indicate that as the subjects get older,their obtained scores by parent and teacher raters on the ADHD-SRS tendto diminish. These correlations were statistically significant, but small.

Means and standard deviations for the ADHD-SRS total scores forchildren and adolescents rated by parents and teachers at three separategrade levels (K-5, 6-8, 9-12) were also calculated. As shown in Table VIII,as the subjects get older, their obtained total scores on the ADHD-SRSbecome lower. Effect size estimates were calculated for this data and arepresented in Table IX. Effect sizes were largest between the K-5 and the9-12 grade levels.

DISCUSSION

Psychometric Characteristics

Data presented in this article regarding the factor structure of theADHD-SRS indicates that a two-factor solution is the most appropriateand clinically interpretable structure for both parent and teacher respon-dent populations. This two-factor solution utilizing an oblique rotation hadthe fewest double loadings and was the most interpretable. The factors werenamed Hyperactive-Impulsive and Inattention, following a visual inspectionof the content of the items which loaded on each factor. Factor 1 consistedof 34 items in the parent data analyses and 35 items in the teacher dataanalyses primarily relating to hyperactivity and impulsivity (i.e., "makes ex-cessive nose," "blurts out," "fidgets and squirms," "restless or overactive").


Factor 2 consisted of 27 items in the parent data analyses and 25 items inthe teacher data analyses primarily to relating inattention (i.e., "has a shortattention span," "has difficulty remaining on task," "is inattentive," "failsto complete homework or school work").

One aspect of the factor analyses that should be mentioned is the mod-erate correlation between the two factors for both parent and teacher sam-ples. This f inding indicates that hyperactivity, impulsivity, andinattentiveness are not distinct, separate behaviors, but instead are moder-ately interrelated.

The two-factor structure obtained for the ADHD-SRS appears, uponobjective visual inspection, to be remarkably similar to the two DSM-IVcategories for ADHD: inattention and hyperactivity-impulsivity. These simi-larities of the ADHD-SRS factor structure with the DSM-IV categoriesprovide further face validity for the ADHD-SRS as the current criteriaused to diagnose ADHD in the childhood population are the categorieslocated in the DSM-IV for ADHD.

The evidence indicates that the ADHD-SRS has strong internal con-sistency and test-retest reliability and moderate cross-informant reliability.The obtained alpha coefficients for the ADHD-SRS total score for parent

Table VIII. Means and Standard Deviations for the ADHD-SRS TotalScore by Grade Level

Parent ratings

Grade level

K-56-89-12

n

5158055

M

46.9035.3018.27

SD

39.6136.8121.58

Teacher ratings

n

2955087

M

50.0131.6226.05

SD

55.0150.7632.89

Table IX. Effect Size Estimates Matrix for the Means and StandardDeviations for the ADHD-SRS Total Scores by Grade Level-Parent

and Teacher Ratings

Grade level

Parent ratingsK-56-8

Teacher ratingsK-56-8

Effect size

K-5 6-8

.30 (small)

.35 (small)

9-12

.94 (large)

.58 (medium)

.54 (medium)

.13 (not significant)

and teacher ratings were .98 and .99 respectively. Virtually any generalguideline for interpreting internal consistency coefficients would indicatethat these internal consistency reliability estimates reflect very strong in-ternal consistency reliability for the ADHD-SRS. High internal consistencymeans that each item in the ADHD-SRS is tapping the same construct(i.e., ADHD) (Mitchell & Jolley, 1988). The temporal stability found forthe ADHD-SRS was also exceptionally high. Finally, the cross-informantcorrelation between parent and teacher ratings approximates the averagecorrelation obtained in most studies for cross-informant ratings (Achenbachet al., 1987).

The data also suggest that the ADHD-SRS has strong content, con-vergent, and construct validity. The content validation procedures utilizingexpert judges and the usability ratings of parents and teachers providesevidence for the validity and usability of the ADHD-SRS. The strong re-lationships found between the ADHD-SRS and three criterion rating scalesprovide substantial supporting evidence of the construct validity of theADHD-SRS as a measure of ADHD symptomatology. In addition, discrimi-nant construct validity of the ADHD-SRS was also obtained through theweak correlations found between the ADHD-SRS and the Anxious-Passivesubscale on the CTRS-39, which clearly appears to be measuring a differentconstruct (i.e., leadership skills and submissiveness) than the ADHD-SRS.

In this research, there was a general tendency for boys to be ratedhigher on the ADHD-SRS than girls of the same age. This tendency wastrue for both parent and teacher responses and was evidenced at all gradelevels. These differences are also reflected in the literature with the higherprevalence rate of ADHD found for boys than for girls (Barkley, 1990).In addition, other rating scales currently used to assess for ADHD amongthe school-age population have also found this phenomenon of males re-ceiving higher subscale and total score ratings than for females of the sameage (Conners, 1990; DuPaul et al., 1996).

As evidenced by the data, as the subjects get older, their obtainedscores by parent and teacher raters on the ADHD-SRS tend to diminish.In other words, subjects' obtained total scores on the ADHD-SRS becamesmaller at later grade levels (i.e., K-12). This finding should not be sur-prising. In later childhood and adolescence, there is often a decline inADHD symptomatology as reported on behavior rating scales (Barkley,1996). This phenomenon may be due to a change in an individual's symp-tomatology (i.e., from "hyperactivity" to "a feeling of inner restlessness"),or it may be that adolescents with ADHD are able to develop adaptivecoping skills to help them better manage their symptomatology. In any case,this phenomenon of decreasing scores on ADHD behavior rating scaleswith age has been well documented (Barkley, 1996; Sleator, 1986).


Clinical Implications of this Research

Based on this research, the ADHD-SRS appears to be a viable ADHDassessment tool for eventual clinical use. The ADHD-SRS has several ad-vantages over many currently existing rating scales. One advantage is thatthe items for the ADHD-SRS are based on the DSM-IV conceptualizationof ADHD and its symptomatology. Also, this rating scale contains 56 itemsdesigned purely to assess for ADHD characteristics, thus generating a morethorough and complete assessment. Although some new rating scales havebeen developed based on the DSM-IV criteria, they vary in how long orthorough they are, and each is bound to have its own "instrument variance"(Merrell, 1994; see Introduction). The results of this preliminary researchindicate that the ADHD-SRS possesses good psychometric properties anda factor structure remarkably similar to the DSM-IV categories for ADHD.Overall, it appears that the ADHD-SRS will eventually be a clinically usefultool for assessment of ADHD with children and adolescents.

Another clinical implication of this research is the moderately strongcorrelation of the ADHD-SRS total score to the Conduct Problem subscaleon the CTRS-39. This finding is consistent with the literature which indicatesa high comorbidity between ADHD and oppositional and conduct disorderedbehaviors (Barkley, 1990; Frick & Lahey, 1991). Thus, these results add tothe mounting evidence of the strong relationship between conduct disorderand ADHD. Clinically it is important to understand this relationship whenattempting to make a differential diagnosis between the two disorders.

Finally, this research adds support to the two DSM-IV ADHD catego-ries, hyperactivity-impulsivity and inattention. Through exploratory factor analy-ses with the ADHD-SRS items, a two-factor structure (Hyperactive-Impulsiveand Inattention) was deemed the most clinically interpretable solution. Thus,this research helps to empirically validate the two DSM-IV categories forADHD and provides further evidence that the DSM-IV is a supportable clas-sification method for diagnosing ADHD in children and adolescents.

Limitations of the Study

In addition to the findings of this research, some potential limitationsshould be addressed. The nature of the sample used in the preliminarynormative group may limit the generalizability of the results. Though anattempt was made to collect data from several U.S. states, the four U.S.geographical regions were not adequately represented. Thus, this prelimi-nary normative group should not be considered to be representative of thegeneral U.S. population. Additionally, the majority of the sample consisted


of children in grades K-7, with the later age ranges (i.e., adolescents) some-what underrepresented. Ideally, it would be desirable to have a more rep-resentative sample of children and adolescent ratings from various areasof the United States, who are stratified on important demographic char-acteristics (i.e., ethnicity, socioeconomic status, etc.). The norm sample usedin the development of the ADHD-SRS is considered preliminary, and amore representative sample is currently being sought. It is unknown howthe limited diversity of this sample affected the results of this research.

Though ideally it would be desirable to have a more representativesampling of participants in the normative group, some recent research hasargued that in fact there is no systematic bias against groups with smalleror no representation in test construction samples. Fan, Wilson, and Kapes(1996) systematically examined the issue of whether or not an ethnicgroup's representation in test construction samples would have an impacton the item selection process in such a way that systematic test bias wouldbe built into the test. Their findings indicated that there was no bias againstthe groups, even those with 0% representation in the test construction sam-ple (Fan et al., 1996). Of course, these findings would apply only to instru-ments that had strong validity and that included meaningful efforts toeliminate content bias in the development process.

Future Directions

The results of the preliminary normative sample provide some evidencefor the reliability, validity, and factor structure of the ADHD-SRS. Further-more, this research has provided the foundation for additional research withthe ADHD-SRS. At this point, the ADHD-SRS should be considered anexperimental research instrument. The development of national norms, ad-ditional reliability and validity studies, and optimum clinical cutoff points isnecessary before this instrument should be used for clinical assessment ofchildren and adolescents. In addition, conducting test-retest reliability stud-ies with longer-term intervals (i.e., 1 month) would also be desirable.

In addition to the exploratory factor analyses run in this research pro-ject, confirmatory factor analyses should also be conducted in the future.In contrast to exploratory factor analysis, confirmatory factor analysis isfrequently used to conform a priori hypotheses based on theory or resultsfrom previous analyses (Floyd & Widaman, 1995; Tabachnick & Fidell,1989). Confirmatory factor analyses are generally noted by the absence offactor rotation (Comrey & Lee, 1992). Confirmatory factor analysis is aprimary method for demonstrating construct validity, not for data reduc-tion. Construct validity is supported if the factor structure of the scales in


the instrument are consistent with the constructs the instrument is pur-ported to measure (Floyd & Widaman, 1995). Also, conducting exploratoryfactor analyses, separating the sample by gender and age, would also bedesirable in order to determine if a similar factor structure is obtained. Itwas not possible to conduct such analyses in this present research as break-ing the sample into subsamples would result in a violation of the 4:1 or5:1 subject-to-item ratio suggested by Floyd and Widaman (1995). In ad-dition, the present sample is only a preliminary sample that does not war-rant such exploration at this time.

Future research should also be conducted on the sensitivity of theADHD-SRS to treatment changes. Specifically, a sample composed of chil-dren and adolescents who have been diagnosed with ADHD should beused. This research could be accomplished through pre and post testing ofsubjects with ADHD either before and after medication administration orbefore and after implementation of behavior management techniques.Treatment sensitivity is another way in which the construct validity of a testmay be demonstrated (Anastasi, 1988).

Summary

In conclusion, this research resulted in the development and investi-gation of the psychometric properties and factor structure of a new behav-ior rating scale designed to measure ADHD, namely, the ADHD SymptomsRating Scale (ADHD-SRS). Additional studies of the ADHD-SRS's test-retest reliability, treatment sensitivity, and confirmatory factor analyses, aswell as the development of national norms, are needed before this ratingscale can be considered fully validated for clinical use. The developmentand refinement of psychometrically adequate and clinically useful assess-ment measures are important to help accurately identify and diagnoseADHD in the childhood and adolescent populations. However, it is im-perative that a link be established between ADHD assessment and specificintervention strategies. Future research that builds upon the present studyshould address this link to increase the development and effectiveness ofinterventions and treatments to the childhood and adolescent populationsdiagnosed with ADHD.

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