PSYC 3250 Lecture Notes - Lecture 14: Quartile, Psychometrics

• School: University of Guelph
• Department: Psychology
• Course: PSYC 3250
• Professor: David Stanley

Document Summary

A loosely structured group of statistics that can be computer for each item in a test. The exact choice and interpretation of the statistics that make up an item analysis are determined by the purpose and nature of the test and the test developer"s objectives. An item analysis can show why a test is reliable or unreliable. Can suggest ways of improving the measurement characteristics of a test. Measuring item diiculty: item-diiculty index: percentage of examinees who answer the item correctly. P value for item = # people answering correctly/# people taking the test. No one gets it right, p = 0. If 60/100 got right q1, diiculty = . 6. 0 = wrong, 1 = right item 1 diiculty = 10/16 = . 63 item 2 diiculty = . 38. I m p l i c at i o n s o f m e a s u ri n g a s a p v a lu e.