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LANGUAGE-ASSESSMENT
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EEX 501 1
Descriptive Statistics
Chapter 4
EEX 501 2
Four Scales of Measurement Nominal
A scale in which the variable values are banes that have no inherent relationship (numbers on a football jersey)
Ordinal A scale that orders or ranks information on some
kind of continuum (best to worse) but does not have equal difference between the ranks (class standing)
Age equivalent, grade equivalent, percentiles
EEX 501 3
Four Scales of Measurement Ratio
Scale on which the magnitude of the difference between any two adjacent points on the scale is the same and has an absolute and logical zero that allows the construction of ratios
All mathematical operations can be performed: add scores, square scores, create ratios (height & weight)
Equal-Interval A ratio scale without an absolute zero: this means that a score
of 50 is not twice as much as a score of 25: many scores used in education and psychology are equal interval
EEX 501 4
Distributions
Distributions of scores may be graphed to represent visually the relationships among the scores in the group. Horizontal axis is is continuum on which individual is measured, vertical axis is frequency
EEX 501 5
Normal Distribution
EEX 501 6
Histogram Graph showing frequency of scores
EEX 501 7
Frequency Polygon
Graph showing distribution of scores
EEX 501 8
Basic Notation
Symbols Add the following Denotes any score Scores in a distribution Frequency of an occurrence Mean of a distribution Variance of a distribution Standard deviation
EEX 501 9
Measures of Central Tendency
Mean Arithmetic average of the scores in a
distribution Median
Score that divides the top 50 percent of the scores from the bottom 50 percent
Mode Score most frequently obtained
EEX 501 10
Measures of Central Tendency
EEX 501 11
Measures of Central Tendency Relationships among mode, median, and mean
for symmetrical and skewed distributions
EEX 501 12
Measures of Dispersion Range
Distance between the extremes of a distribution Variance (S2)
Average squared distance of the scores from the mean
Standard Deviation (positive square root of the variance) A unit of measure Can be measured as a standard deviation unit from
the mean
EEX 501 13
Standard Deviation
EEX 501 14
Mean
EEX 501 15
Measures of Dispersion
EEX 501 16
Correlation Definition
Quantify relationship between variables Correlation coefficient
Tell what extent any two variables go together, the extent to which changes in one variable are reflected by changes in the second variable
Pearson-product moment correlation coefficient Most common coefficient
Zero correlation No relationship
Causality Refers to one thing causing another; the presence of correlation does
not imply causality
17EEX 501
Quantification of Test Performance
Chapter 5
18EEX 501
Norm Referenced Assessment Developmental scores
Raw scores that have been transformed into age equivalents, grade equivalents or developmental quotients
Scores of relative standing Percentile rank Standard score
• Z score• T score• Stanines
19EEX 501
Criterion-Referenced Assessment
Single skill scores Multiple skill scores Global ratings
20EEX 501
Norms
Chapter 6
21EEX 501
Representativeness General characteristics and experience;
dependent on construct being measured Age Grade in school Gender Acculturation of parents Geography Race & culture intelligence
Relevant special characteristics: some characteristics of the sample and population are important only for particular types of tests
22EEX 501
Technical Considerations Finding people
Cluster sampling (schools) Proportional representation
Various kinds of people should be included in the same proportion in the sample as they occur in the general population
Number of subjects # should be large enough to guarantee stability
Smoothing norms Remove unwanted fluctuations in the shapes of the age or grade
distributions by adjusting the relationship between standard scores and percentiles
Age of norms Represent population: skills & levels change
Relevance of norms; relevant for what the is supposed to measure
23EEX 501
Using Norms Correctly Tester must select tables based on
Age grade
24EEX 501
Reliability
Chapter 7
25EEX 501
Reliability Definition: generalizing what we see today
under one set of conditions to other occasions and conditions (reliability coefficient) Generalizing to different time: stability Generalizing to different item samples
• Internal consistency Factors affecting reliability
Test length: more items greater reliability Test-retest interval:interval between tests Constriction or extension: range of ability Guessing: responding randomly to items Variation within the testing situation: error introduced into the results of testing:
headaches, sick, misunderstand directions
26EEX 501
Reliability Determining which reliability method to use
Type of generalization we wish to make Considerations
• Stability: retest after two weeks• Alternate form reliability: different form of test• Correlation coefficient
Standard error of measurement Estimate the amount of each type of error associated with true scores
Estimated true scores We never know a subject’s true score Confidence intervals
• The likelihood that a person’s true score might be found within a specified range• Establishing confidence intervals
27EEX 501
Reliability Difference scores
We might be interested in differences between two scores: reading achievement commensurate with her intellectual ability
Desirable standards Important for test authors to present sufficient information in
test manuals for the user to interpret test results accurately Provide sufficient reliability data to allow user to evaluate
reliability of the test scores that are to be interpreted• .60 group data• .90 individual data• .80 screening
EEX 501 28
Validity
Chapter 8
EEX 501 29
Validity Definition: appropriateness, meaningfulness,
and usefulness of the specific inference that can be made on the basis of observation
Methods of validating test inferences Content validity: test’s items actually represent the
domain it measures Criterion related validity:extent to which a person’s
performance can be estimated from the performance on the assessment
Construct validity: extent to which a test measures a theoretical trait (IQ)
EEX 501 30
Validity Factors affecting generalizability Reliability: upper limits of a test’s validity
All valid tests are reliable Unreliable tests are not valid Reliable tests may or may not be valid Valid procedures measure the traits they are designed to
measure Systematic bias
Method used to measure a skill or trait is often believed to affect what score a child will receive
A true score can be considered a composite of trait variance and method of measurement variance
EEX 501 31
Responsibility for Valid Assessment Valid use of assessment procedures is the
responsibility of: The author The user of the assessment process
Validity is the only technical characteristic of a assessment in which we are interested We must know whether inferences drawn from an
assessment are accurate
EEX 501 32
Adapting Tests to Accommodate Student with
Disabilities
Chapter 9
EEX 501 33
Concerns about Testing Adaptations Changes in student population Changes in educational standards Need for accurate measurement Participation
Standards apply to all students Accommodation
Adapting or modifying assessment measures
EEX 501 34
Factors affecting Accurate Assessment
Ability to understand the assessment Ability to respond to assessment stimuli Nature of the norm group Exposure to curriculum being tested Legal considerations Current practice decisions Recommendations for participation
EEX 501 35
Testing Accommodations Current practice
Extended time Braille Tape recorder Magnifying glass
Recommendations Student’s native language Make accommodations so that purpose of testing is
not impaired Make normative comparisons
EEX 501 36
Making Entitlement Decisions
Chapter 16
EEX 501 37
Rationale for Entitlement Lack of academic success No-fault failure Political action Problems associated with the criteria
EEX 501 38
Entitlements Special services Different outcome expectancies Procedural safeguards Special fiscal arrangements
EEX 501 39
Determining Eligibility for Services
Official exceptionalities• Autism• Mental retardation• Specific learning disability• Emotional disturbance• Traumatic brain injury• Speech or language impairment• Visual impairment• Deafness and hard of hearing• Orthopedic impairments• Other health impaired• Deaf-blindness• Multiple disabilities• Developmental delayed
EEX 501 40
Determining Eligibility for Services
Establishing educational need Establishing exceptionality Process of determining exceptionality
EEX 501 41
Assessment of Intelligence: Overview
Chapter 17
EEX 501 42
Intelligence Tests as Samples of Behavior
Assess a student’s capacity to profit from instruction
Samples behavior from a larger domain of behavior
One can not possibly assess every item in a domain
EEX 501 43
Effect of Pupil Characteristics on Assessment of Intelligence
Acculturation is the most important characteristics to consider in evaluating performance on IQ tests
Acculturation refers to an individual’s particular set of background experiences and opportunities to learn
EEX 501 44
Behaviors Sampled by Intelligence Tests
Discrimination Generalization Motor behavior General Knowledge Vocabulary Induction Comprehension
Sequencing Detail Recognition Analogical Reasoning Pattern Completion Abstract Reasoning Memory
EEX 501 45
Dilemmas in Current Practice
Currently marked by controversy Understanding what that test assesses
EEX 501 46
Assessment Of Intelligence: Individual Tests
Chapter 18
EEX 501 47
Why do We give Individual Intelligence Tests?
General intelligence tests Stanford-Binet (SB) 4th edition Weschler Scales (WAIS,WISC,WPPSI,WASI) Detroit Tests of Learning Aptitude Cognitive Assessment System
EEX 501 48
Non-Verbal Intelligence Tests
Comprehensive Tests of Nonverbal Intelligence
Leiter International Test of Non-verbal Intelligence Universal Nonverbal Naglieri Nonverbal Ability Test Peabody Picture Vocabulary Test