Psychological Testing Characteristics of Psychological Testing 13.1

Characteristics of Psychological Tests Must exhibit reliability, validity, and standardization to be useful Fairness and usefulness of a test depend on Reliability Test’s consistency Same results under variety of differing circumstances Three basic ways to determine reliability Test-retest Interscorer-scorer Interscorer- different test graders Scorer- same test grader Split-half Dividing test items in half and scored separately

Validity Standardization Ability of a test to measure what it is intended to measure Chief method for measuring validity is to find out how well a test predicts performance- predictive validity A test designed for measuring management ability Will the people who score high make good managers? Standardization Administered and scored same way every time Refers to establishing the norm, or average score, for a large group

Why must raw scores be transformed into percentiles? Percentile system Ranking of test scores that indicate the ratio of scores lower and higher than a given score Scores actually achieved are ranked in order from highest to lowest Each score is compared with list and assigned percentile according to the percentage of scores that fall above or below this point Child scores 32/50 on a vocabulary test How does this relate to other children that were tested If most children scored 45/50, then score is low; 20/50, then score is high If 32 were the top score, then it would be in the 100th percentile If half the children scored 32 or below, then 32 is in 50th percentile Therefore, a raw score must be transformed into percentiles because it does not indicate where the student ranks among the students who took the same test