PSYC 3250 Study Guide - Final Guide: Standard Written Form, Mental Rotation, Longitudinal Study

• School: University of Guelph
• Department: Psychology
• Course: PSYC 3250
• Professor: Deborah Powell

Document Summary

Steps in test development: test conceptualization, test construction, test tryout, item analysis, test revision. Purpose of item analysis: can show why a test is reliable or unreliable, can suggest ways to improve the measurement characteristics of a test. Item analysis technique for questions with right/wrong answers: item difficulty, item discrimination, distractor analysis. Item analysis for self-report scales: item mean, corrected item-total correlation. Item analysis for either right/wrong of self-report: item reliability index, cronbach"s alpha. Item difficulty: in psychometrics, difficulty is defined in terms of the number of people who answer each test item correctly, more people getting answer correct = easy. Measuring item difficulty: item difficulty index: percentage of examinees who answer the item correctly, formula: p value for item = # of people answering the item correctly / # of people taking the test. Item discrimination index is simply the diff between these two percentages. # people expected to choose each distractor =