Nursing students’ mathematic calculation skills

Nursing students’ mathematic calculation skills

Lynde Rainboth a,*, Chris DeMasi b,1

a BryanLGH College of Health Sciences, Nebraska Wesleyan University, USAb BryanLGH College of Health Sciences, USA

Accepted 20 July 2006

Summary This mixed method study used a pre-test/post-test design to evaluatethe efficacy of a teaching strategy in improving beginning nursing student learningoutcomes. During a 4-week student teaching period, a convenience sample of 54sophomore level nursing students were required to complete calculation assign-ments, taught one calculation method, and mandated to attend medication calcu-lation classes. These students completed pre- and post-math tests and a majormedication mathematic exam. Scores from the intervention student group werecompared to those achieved by the previous sophomore class. Results demonstrateda statistically significant improvement from pre- to post-test and the students whoreceived the intervention had statistically significantly higher scores on the majormedication calculation exam than did the students in the control group. The evalu-ation completed by the intervention group showed that the students were satisfiedwith the method and outcome.

�c 2006 Elsevier Ltd. All rights reserved.This article appears in a joint issue of the journals Nurse Education Today Vol. 26,No. 8, pp. 655–661 and Nurse Education in Practice Vol. 6, No. 6, pp. 347–353.

KEYWORDSMedication calculationskills;Nursing student;Calculation method;Mathematical skills

Introduction

From the very beginning of the nursing profession,the nurse has been the last line of defense againstmedication administration errors. The nurse mustnot only know the reasoning, incompatibilities,and the effects of the medication, but also be ableto perform medication calculations to assure thedosage is safe for the client. It has been discovered

that more than one in six medication errors entailerrors of calculation (Capriotti, 2004, p. 63). Medi-cation calculations in nursing can be a challengingskill to maintain, due to technological systems de-signed to facilitate medication administration, suchas, the intravenous pump that calculates drip ratesand as a result reduces mathematical practice inthe clinical setting (Cartwright, 1996). Recent andpast nursing research has consistently found thatpracticing nurses of various fields and studentnurses from various types of nursing schools,showed difficulties with basic mathematical skillsand medication calculation abilities (Bayne and Bin-

1471-5953/$ - see front matter �c 2006 Elsevier Ltd. All rights reserved.

* Tel.: +1 605 688 4083; fax: +1 605 528 3958.E-mail addresses: [email protected] (L. Rain-

both), [email protected] (C. DeMasi).1 Tel.: +1 402 481 8705.

Nurse Education in Practice (2006) 6, 347–353

www.elsevierhealth.com/journals/nepr

NurseEducationin Practice

dler, 1988; Bindler and Bayne, 1991; Blais and Bath,1992; Craig and Sellers, 1995; Gillham and Chu,1995; Santamaria et al., 1997).

Literature

The reviews of various studies have found that ba-sic mathematic proficiency of college students can-not be assumed. As early as the mid 1960s, Mundayand Hoyt (1965) performed a study on beginningstudent nurses from seven schools of nursing, andfound that mathematics was the lowest of theirtest scores. To examine the discrepancy amongthe various colleges on entry requirements, Hilton(1999) and Hutton (1998) assessed if nursing col-leges have the ability to predict competence inmathematic calculations. The subjects in bothstudies completed the General Certificate of Sec-ondary Education (GCSE) diagnostic mathematictest. The results of both studies suggested that pa-per qualifications on mathematics, other thanthose above GCSE grade C or equivalent cannotbe relied upon to predict performance in a test ofmathematics required for nursing. However, itwas found that with the use of revision tutorialand self-help booklets in basic mathematics, testscores can be raised to acceptable levels in a shortperiod of time.

Today educators are continually confronted withstudents who lack basic mathematical skills. Gill-ham and Chu (1995) assessed the basic math skillsof pre-registered second year nursing students andfound that these students were deficit in the basicmath ability of division, formula use, and multipli-cation of fractions. A similar study done by Brown(2002), found that many of the nursing studentsare entering college with a lack of understandingof the very basic below seventh grade math skills,involving fractions, decimals, and percents. A studyby Blais and Bath (1992) was conducted to assessthe mathematical ability, conceptualization, andthe difficulty involved in measurements amongnursing students. The results found that 89% ofthe sample did not receive a passing score and mosthad difficulty with basic math skills and conceptual-izing the problem to set up the computation to pro-vide the correct dose.

The various mathematical needs and learningstyles of each nursing student showed the necessityfor faculty to assess students prior to developinginstructional strategies to meet student’s needs(Conner and Tillman, 1990; Jeffries, 2001). Bathand Blais (1993) found that the consistent use ofone formula throughout the entire curriculum for

solving dosage calculation problems reduced con-fusion and prevented mathematical inaccuracies.Similarly, Worrell and Hodson (1989) discoveredthat variations found between teaching methodol-ogies of nursing faculty and the usage of differentformulas had a negative effect on nursing students’mathematical calculation abilities, creating confu-sion among the students required to perform multi-ple step calculations. Craig and Sellers (1995) alsofound that teaching one medication calculationformula supported mastery of basic mathematicalskills.

Richardson and Suinn (as cited in Pozehl, 1996,p. 37) stated ‘‘Deficiency in conceptual ability re-lated to mathematics may also be compoundedby anxiety, which has been shown to interfere withthe manipulation of numbers and solving of mathproblems’’. To follow through with those findings,Pozehl (1996) conducted a study to assess howmathematical anxiety affects nursing studentsand nonhealthcare students. The results of thestudy showed that nursing students had a highermathematic anxiety level, but no statistical signif-icance found in the difference of anxiety levelamongst the subjects. The researcher concludedthe need for early identification of mathematicalcalculation problems throughout nursing programsto explore ways to reduce mathematical anxiety.

Theoretical background

This study was based on the premise of informationprocessing theory. This theory states that if infor-mation and skills need to be retrieved to completecomplex problem-solving situations, they must bepracticed and learned thoroughly so that automa-ticity, mastery learning, and enhanced studentself-efficacy are attained (Ormrod, 2003). The ra-tio and proportion problem-solving method is aknown mathematical formula that is incorporatedin elementary and high school curriculum (Matos,2004). This problem-solving method follows thestep-by-step concept of the information processinganalysis, in which the student defines the problem,identifies appropriate method of setting up theproblem, retrieves the relevant numbers, and thenapplies the problem solving operations (see exam-ple in Appendix A).

Purpose

To determine whether mandatory medication cal-culation classes and required weekly mandatory

348 L. Rainboth, C. DeMasi

calculation assignments with the use of one calcu-lation method will improve the performance onpre- to post-tests and major medication calcula-tion exam completed by beginning nursing stu-dents. To verify whether other factors influencedstudents’ calculation knowledge and ability priorto the intervention and to determine whether thestudents are able to retain medication calculationknowledge and skills.

Methodology

Participants

A convenience sample of 99 sophomore level diplo-ma nursing students, who took a medication calcu-lation course at a Midwestern diploma college, wasused in the study. The intervention group consistedof 54 current sophomore level diploma nursing stu-dents and the control group consisted of 45 nursingstudents from the previous sophomore level diplo-ma class.

Instruments

Medication calculation skills performance wasmeasured with a 14-item multiple-choice com-pleted pre- and post-test intervention. The testcontained items that required the use of a problemsolving formula to resolve medication calculationproblems. The test also required an understandingof metric system conversions, and fractions anddecimals, all necessary skills for conducting medi-cation calculations. An equivalency table was pro-vided for the medication calculation skillsperformance pre- and post-test. Content validitywas established through a review by expert nurseeducators in mathematics. Internal consistencywas established by the Cronbach’s Alpha reliabilityof 0.674 for this instrument.

The final medication calculation skills perfor-mance was measured by the sophomore level ma-jor medication calculation exam that consisted of10 fill-in-the-blank questions. The questions in-cluded single step and multiple step calculationsfor tablet dosages, liquid medication dosages,and intramuscular and subcutaneous dosages. Thesame major medication calculation exam was givento both the intervention and control group of thestudy. Content validity was established through re-view by a group of expert nurse educators in math-ematics and Cronbach’s Alpha reliability was notedat 0.135. This low score could be due to the large

percentage of students who received 100% on theexam.

Medication calculation skills retention was mea-sured by the junior level major medication calcula-tion exam that consisted of 10 fill-in-the-blankquestions. The questions included single step andmultiple step calculations for tablet dosages, liquidmedication dosages, and intramuscular and subcu-taneous dosages. The same major medication cal-culation exam was given to both the interventionand control group of the study. Content validitywas established by a group of expert nurse educa-tors in mathematics and Cronbach’s Alpha reliabil-ity was noted at 0.544. This low score could be dueto the large percentage of students who received100% on the exam.

Student perceptions of the medication calcula-tion education strategies were measured by an11-item 4-point Likert item survey that also in-cluded opened exploratory questions. Internal con-sistency was established by the Cronbach’s Alphareliability of 0.768 for this instrument.

Procedure

The study was approved by the Dean of the collegeand the students in the intervention group were in-formed of the complete schedule and goal of thecourse. The students were also notified prior tothe course that the test scores and surveys wouldbe confidential and used to evaluate the teachingstrategy. It was noted that all students partici-pated and no objections were verbalized.

The course took place in a well lit large class-room, which could seat up to 100 people. Duringthe first class session the expert nurse educator ori-ented the students to the course and provided theassignment plan with due dates. The assignmentplan included the completion of the basic mathe-matical calculation assignments, including ratioand proportion worksheets to be handed in everyweek for 3 weeks. Prior to the completion of thefirst class the students completed the 14-itemmedication calculation pre-test. During the testingthe students were allowed to use the equivalencytable and a calculator, but instructed to write-out their calculations on the exam. All gradingand instructions were given by one nurse educatorwho is an expert on medication calculations andthe current educator of the sophomore level med-ication calculation course. The students were in-structed to use the ratio and proportion methodwhen conducting medication calculations. At theend of every week the nurse educator correctedthe assignments and provided written feedback

Nursing students’ mathematic calculation skills 349

for the students. On the third week a mandatorymedication calculation review class was con-ducted, which focused on problem areas noted onthe weekly assignments. Following the class eachstudent completed the 14-item medication calcula-tion post-test which was identical to the pre-test.

The students who missed more then two ques-tions on the post-test were required to attend an-other medication calculation review class and doadditional remedial homework. The review classwas scheduled prior to the major medication calcu-lation exam and focused on the areas of concernnoted on the post-test. On the 10-item sophomorelevel major medication calculation exam the stu-dents were allowed to use a calculator, but wererequired to write out their calculations on theexam. The equivalents table was not provided dur-ing the exam and the students were allowed asmuch time as needed to complete the exam.Immediately after the exam each student com-pleted an 11-item 4-point Likert survey.

To assess student retention of medication calcu-lation skills, each student (n = 93) took the juniorlevel 10-item major medication calculation examat the beginning of their junior level course. Priorto the beginning of the study the instructors ofthe junior level nursing course were informed ofthe study and advised to provide the same instruc-tions to the intervention group as had been pro-vided to the control group. On the 10-item majormedication calculation exam the students were al-lowed to use a calculator, but were required towrite out their calculations on the exam. Theequivalents table was not provided during the ma-jor medication calculation exam and the studentswere allowed as much time as needed to completethe exam.

Results

Description of subjects

The Nurse Entrance Test (NET) is given to all stu-dents prior to the start of courses in the nursingprogram. The NET is a diagnostic tool to assessthe academic and social skills of students who areapplying to the school of nursing. The NET evalu-ates six content areas, such as, basic math skills,reading comprehension for science textbooks,test-taking ability, stress levels, social interaction,and learning style (BryanLGH College of Health Sci-ences, 2004). A t-test for equality of means showedthat both groups of students, control and interven-tion were similar on their comprehension of math

(t = 0.246, df = 96, p = 0.807), decimal operations(t = 0.156, df = 96, p = 0.876), fraction operations(t = 0.16, df = 96, p = 0.988), reading comprehen-sion (t = 0.924, df = 92, p = 0.358), and numberconversions (t = 0.550, df = 94, p = 0.584) with amean score of all students at 66% (SD = 16.23).The intervention group consisted of 49 womenand five men and the control group consisted of41 women and four men. The mean age of theintervention group was 25.17 years (SD = 7.02) ascompared to a mean age of 24.44 (SD = 5.25) yearsfor the control group.

Findings

Use of a paired t-test demonstrated that the inter-vention group scored statistically significantly bet-ter on the 14-item post-test than on the pre-test(t = 8.5, df = 53, p < 0.0001) (see mean scores andSD of intervention group’s pre-test and post-testin Table 1). The intervention group’s scores onthe sophomore level major math exam were com-pared to the control group’s scores and showedminimal difference. When the NET exam resultsof the math comprehension, decimal operations,fraction operations, number conversions, and read-ing composition were used as covariates the twogroups still demonstrated equivalent scores onthe sophomore level major math exam (controlgroup’s mean = 9.2; intervention group’smean = 9.3; F = 0.57, df = 1, p = 0.45).

Three months after the sophomore nursingcourse, both the intervention group and the controlgroup completed the same junior level medicationcalculation exam. When comparing the interven-tion group’s exam scores with the control group’sexam scores, the intervention group achieved sta-tistically significant higher scores than the controlgroup (see both groups’ mean scores and SD inTable 2).

The intervention group’s NET exam results formath comprehension, decimal operations, fractionoperations, number conversions, and reading com-position were moderately correlated with theirsophomore level medication calculation exam re-sults, but were not well correlated with their juniorlevel medication calculation exam results (see thePearson Correlation in Table 3).

The results of the intervention group’s 11-item4-point Likert style survey had positive findings.When assessing the key concepts of the survey,53.1% of the intervention group strongly agreedand 46.9% agreed that homework was helpful,59.2% agreed and 28.6% strongly agreed that themandatory review was helpful, and 50% agreed


and 42% strongly agreed that learning a single med-ication calculation method was preferred (see sur-vey results in Table 4).

A portion of the survey asked the interventiongroup if they only studied alone or studied aloneand in groups. When comparing the post-testscores of those who studied alone with thosewho studied alone and in groups, the results ofthe scores did not reach statistical significance(t = 1.87, df = 49, p = 0.067) with the post-test,as with the sophomore level medication calcula-tion exam. The final portion of the survey hadan open exploratory question and 9 out of 54 stu-dents in the intervention group provided com-ments regarding the medication calculationcourse. Three students commented that the med-ication calculation homework was helpful; onestudent mentioned that the homework allowedfor medication calculation practice, and one stu-dent came to the realization of the importanceto correctly calculation medication dosages. Inaddition, three students mentioned that the re-views of basic mathematical skills were helpful,and two students stated that they felt it wouldhave been beneficial to learn more than one med-ication calculation method.

Discussion

Mathematical calculation skills of nurses have beena concern for many years. This concern should beaddressed early in nursing schools. The results ofthis study gave probity to the theory that the defi-ciency of mathematical calculation skills can beimproved at the nursing school level. The study’sresults provided evidence that an educationalintervention can help students attain and retainmath calculation. The intervention group showededucationally significant improvement from pre-test to post-test after the teaching intervention.A baseline was established by examining both

Table 1 Mean and standard deviation of interven-tion group’s pre-test and post-test

N Meana SD

Pre-test 54 11.3519 2.16453Post-test 54 13.0926 1.40442a Significantly different (t = �8.5, df = 53, p < 0.0001).

Table 2 Means and standard deviations by groups

Sophomorelevel exama

Junior levelexama,b

Intervention group 9.3 (0.80) 9.9 (0.39)Control group 9.2 (0.99) 9.2 (1.06)a Data in table is mean (SD).b Statistically significant t = 4.2, df = 51, p < 0.0001.

Table 3 Pearson R correlation: intervention group’sNET exam subscores with the sophomore and juniorlevel medication calculation exams

Sophomoreexam

Juniorexam

NET comprehensive math% 0.410a 0.137NET decimal operations% 0.295a 0.137NET fraction operations% 0.347a 0.106NET number conversions% 0.380a 0.120NET composition reading% 0.271a 0.140a Correlation is significant at the 0.01 level (two-tailed).

Table 4 Frequency table of responses on the 11-item Likert survey

Strongly agree (%) Agree (%) Disagree (%) Strongly disagree (%)

Study guide was helpful 53.1 46.9 0 0Homework was helpful 40 54 6 0Mandatory review was helpful 28.6 59.2 10.2 2Math instruction decreased anxiety 18.4 67.3 14.3 0My math ability is high 17.6 43.1 35.3 3.9I was prepared for this course 30 68 2 0Pre-test was useful 49 45.1 5.9 0Post-test was useful 43.1 54.9 2 0Understood ratio and proportion formula 44 52 4 0Prefer single method 42 50 8 0Prefer multiple methods 6 12 54 28


groups’ NET exam results, showing no statisticallysignificant difference on incoming knowledge base.It is important to note the baseline findings to sub-stantiate the validity of the intervention results.Also, the Pearson Correlation showed that theintervention group’s results on the sophomore levelmedication calculation exam may have been influ-enced by their pre knowledge base, however, whenreviewing their junior exam results there was noevidence of pre knowledge influence. This may bedue to the teaching intervention provided to theintervention group.

The intervention group scored statisticallysignificantly higher on the junior level exam com-pared to the control group. This showed a higherlevel of retention among the intervention group,substantiating the fact that providing theseteaching interventions can aid in promoting anunderstanding and preventing confusion when cal-culating medication doses in subsequent coursesor clinical settings.

Students expressed satisfaction with the medi-cation calculation educational methods. Studentsin the intervention group felt the mandatoryreview class, the study guide, and mandatoryhomework were beneficial in preparing for thesophomore level medication calculation exam. Inaddition, it was noted that the majority of the stu-dents felt that the teaching intervention helpeddecrease their anxiety regarding the exam and im-proved their perception of their own math ability.The majority of students felt that learning andmastering one method of medication calculationswas preferred. These results run counter to opin-ions offered in books that several different meth-ods of medication calculation are preferable toone method (Hegstad and Hayek, 2001).

On the survey the subjects reported that over53% studied alone and in groups and 47% onlystudied alone. When comparing the scores of thesophomore level medication calculation exam,pre-test, and post-test of those two groups, the re-sults for the post-test demonstrated that thosewho studied alone performed better than thosewho studied in groups. However, this result didnot quite reach statistical significance.

The final portion of the survey included an openexploratory question and 9 out of 54 students in theintervention group provided comments regardingthe medication calculation course. Three themeswere established that provided additional supportto past and present mathematical medication cal-culation studies. These comments included thatthe teaching strategies were helpful and strength-ened the realization of the importance of correctlycalculating medication dosages to protect client

safety. Finally, the majority of the students feltthat knowledge of one medication calculationmethod was more useful and less confusing thanmultiple methods.

Conclusion

The results of this study should encourage nursingfaculty to review basic mathematical skills withnursing students, to be consistent with one medica-tion calculation method to decrease confusion, andmathematical anxiety. In addition, the results ofthe study point to the need to provide mandatorymedication calculation classes and mandatoryhomework to promote further practice, improvemathematical calculations, and promote masteryof calculating various forms of medication. How-ever, this study was possibly limited by a conve-nience sample from one educational setting andthe sample being predominantly Caucasian femalenursing students. In addition, internal validity waspossibly threatened by the pre-test and post-test,due to containing the same questions in the sameorder, which may have caused the participants tobecome sensitized to the problems.

Acknowledgements

The authors thank June Smith RN, PhD, employedat BryanLGH College of Health Sciences, and JeffLang, employed at Nebraska Wesleyan University,for their support.

Appendix A. Example of ratio andproportion calculation

Amoxicillin 500 mg is ordered. Client has 250 mgcapsules. How many capsules should she take?

(1) 250 mg1 cap

¼ 500 mgx cap

(2) 250x = 1 · 500(3) 250x = 500(4) x ¼ 500

250

(5) x = 2 caps

References

Bath, J.B., Blais, K., 1993. Learning styles as a predictor of drugdosage calculation ability. Nurse Educator 18 (1), 33–36.

Bayne, T., Bindler, R., 1988. Medication calculation skills ofregistered nurses. The Journal of Continuing Education inNursing 19 (6), 258–262.


Bindler, R., Bayne, T., 1991. Medication calculation ability ofregistered nurses. Journal of Nursing Scholarship 23 (4), 221–224.

Blais, K., Bath, J.B., 1992. Drug calculation errors of baccalau-reate nursing students. Nurse Educator 17 (1), 12–15.

Brown, D.L., 2002. Does 1 + 1 still equal 2: A study of themathematic competencies of associate degree nursing stu-dents. Nurse Educator 27 (3), 132–135.

BryanLGH College of Health Sciences, 2004. Understanding TheNurse Entrance Test (NET).

Cartwright, M., 1996. Numeracy needs of the beginning regis-tered nurse. Nurse Education Today 16 (2), 137–143.

Capriotti, T., 2004. Basic concepts to prevent medicationcalculation errors. MEDSURG Nursing 13 (1), 62–65.

Conner, S.E., Tillman, M.H., 1990. A comparison of algorithmicand teacher-directed instruction in dosage calculation pre-sented via whole and part methods for associate degreenursing students. Journal of Nursing Education 29 (1), 31–36.

Craig, G.P., Sellers, S.C., 1995. The effects of dimensionalanalysis on the medication dosage calculation abilities ofnursing students. Nurse Educator 20 (3), 14–18.

Gillham, D.M., Chu, S., 1995. An analysis of student nurse’smedication calculation errors. Contemporary Nurse 4 (2),61–64.

Hegstad, L.N., Hayek, W., 2001. Essential Drug Dosage Calcu-lations. Prentice-Hall, New Jersey.

Hilton, D.E., 1999. Considering academic qualification in math-ematics as an entry requirement for a diploma in nursingprogramme. Nurse Education Today 19 (7), 543–547.

Hutton, B.M., 1998. Do school qualifications predict compe-tence in nursing calculations?. Nurse Education Today 18(1) 25–31.

Jeffries, P.R., 2001. Computer versus lecture: A comparison oftwo methods of teaching oral medication administration in anursing skills laboratory. Journal of Nursing Education 40 (7),323–329.

Matos, L.E., 2004. Word problems dealing the ratio andproportion. Retrieved January 3, 2006, from Yale-New HavenTeachers Institute Web site: http://www.yale.edu/ynhti/curriculum/units/2004/5/04.05.08.x.html.

Munday, L., Hoyt, D.P., 1965. Predicting academic success fornursing students. Nursing Research 14 (4), 341–344.

Ormrod, J.E., 2003. Educational Psychology: Developing Learn-ers, fourth ed. Merrill-Prentice Hall, Upper Saddle River, NJ.

Pozehl, B.J., 1996. Mathematical calculation ability and math-ematical anxiety of baccalaureate nursing students. Journalof Nursing Education 35 (1), 37–39.

Santamaria, N., Norris, H., Clayton, L., Scott, D., 1997. Drugcalculation competencies of graduate nurses. Collegian 4 (3),18–21.

Worrell, P.J., Hodson, K.E., 1989. Posology: The battle againstdosage calculation errors. Nurse Educator 14 (2), 27–31.


Documents

Nursing students’ mathematic calculation skills