1. Getting Started Copyright © 2007 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Research In Personality Focus on Measurement This multimedia product and its contents are protected under copyright law. The following are prohibited by law: any public performance or display, including transmission of any image over a network; preparation of any derivative work, including the extraction, in whole or in part, of any image; any rental, lease, or lending of the program.

2. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Measurement of Attributes Measure attributes of the object For example, measurement of –length (to right) –weight (to right)

3. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Psychometric Theory A.Theories of how to measure abstract, mental phenomena B.The central equation: X = T + e X, the obtained test score T, the true score e, the error score

4. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Reliability in Physical Measurement Things to Remember Measuring a Window for Window Blinds: Use a steel tape for accuracy. Measure the exact width of the window at 3 different places. Make all measurements to the nearest 1/8 inch.

5. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Definitions of Reliability Informal: that a test measures what it measures with consistency Formal: the correlation, r, between the true score and the obtained score.

6. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY (A hard) Pop Question When is a mental test perfectly reliable? A. X = 0 B. T = 0 C. e = 0 D. X = T

7. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Measurement Validity A.Definition: That a test measures what it is supposed to measure B.Types of Validity: 1.Content 2.Criterion 3.Structural 4.Construct

8. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Content Validity A test’s items accurately sample from the content domain

9. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Criterion (or Predictive) Validity A test predicts a specific, measurable outcome, such as a life variable Examples: marriage grade point average occupational success (or postdicts it, or concurrently indicates it)

10. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Pop Question A.Which of the following correlations between two variables is most useful for the purposes of predicting one from the other? a) -.75 b).00 c) +.25 d) +.50

11. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Structural Validity A test measure the number of things it claims to measure Technical Test: Factor Analysis… –How many factors does a test measure? –Factor: An “underlying” variable

12. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY Construct Validity A test behaves the way it is supposed to behave according to theoretical statements, over numerous circumstances and tests

13. What Does It Mean to Measure Personality? © Copyright 2006 Allyn & Bacon Mayer’s Personality: A Systems Approach PART 1: EXPLORING PERSONALITYCHAPTER 2: RESEARCH IN PERSONALITY ~ end ~