CHAPTER 3: Practical Measurement Concepts Assessing Students with Special Needs Fifth Edition John J. Venn University of North Florida © 2014, 2007, 2004 by Pearson Education, Inc. All Rights Reserved

Overview Basic Statistics Reliability Validity Norm and Criterion-Referenced Assessment Practical Measurement Concepts

Overview Precisely assessing students with special needs requires knowledge of measurement concepts Key concepts include of basic statistics, accuracy in assessment, and the effectiveness of tests and evaluation procedures

Basic Statistics Statistics Summarize and give meaning to test scores and other assessment results Distributions Describe the pattern of test scores Normal distributions (bell-shaped curve)

Basic Statistics Measures of central tendency Describe the most frequently occurring scores Averages Mean, median, mode Measures of variability Summarize the spread or dispersion of scores Standard deviation and standard error of measurement

Reliability Accuracy and consistency of scores from tests and other other assessments Are the scores from the test consistent? Specific measures include test-retest, alternate-form, split-half, and interrater reliability

Validity Effectives of scores from tests and other assessments Does the test measure what it is supposed to measure? Types of validity Content Criterion-related Construct Consequences of testing

Norm-Referenced Assessment Interpreting performance in relation to the performance of others Relates individual scores to the average scores of the norm group Norm groups are carefully selected groups of students Places or ranks students compared with other students

Criterion-Referenced Assessment Interprets performance in relation to a functional level or criterion Closely related to instruction Teachers use this daily in teaching lessons and monitoring student progress

Checklist of Practical Measurement Concepts Applications Checklist of Practical Measurement Concepts Is the testing time reasonable? Is the cost of the test reasonable? Is the test well designed with high-quality materials? Is the reading level of the test appropriate? Does the test include enough items to accurately measure skills and abilities?

Fairness in Assessment Equity of tests for all students Difficult to define fairness in testing Bias in testing Item bias Internal bias External bias

Summary Statistics summarize and give meaning to test scores Reliability and validity are essential technical qualities of tests and assessments Norm and criterion-referenced assessment are two different ways to interpret performance Fairness is the most important practical, applied consideration in assessment