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Measurement in Psychology: Validity

Measurement in Psychology: Validity. Lawrence R. Gordon Psychology Research Methods I. You have a reliable measure…. It gives you a consistent measure of something every time that you measure it SO WHAT??? Is that all a measure needs to do?. Validity.

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Measurement in Psychology: Validity

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  1. Measurement in Psychology:Validity Lawrence R. Gordon Psychology Research Methods I

  2. You have a reliable measure… • It gives you a consistent measure of something every time that you measure it • SO WHAT??? • Is that all a measure needs to do?

  3. Validity • NOTE: a scale CAN be reliable but not valid; it CANNOT be unreliable scale, but be valid! • In short, a measure has to measure what it claims to measure (or what you claim it measures) • How can you show others that you are measuring what you say you are measuring? • Example

  4. SAT’s and College Potential • How can we show that SAT’s are actually measuring college potential?

  5. Types of Validity • Content/Face validity • does it look like it is measuring what it should? • Examples (Polygraph measures lying through GSR, EEG, heart rate? Reaction time measured with a stopwatch?) • Does the content make sense in measuring the construct? • Content/Sampling Validity • Where did the content come from? • Examples (Why do we need to know insane vocabulary words and geometry on the SAT’s? Who wrote those questions?)

  6. Types of Validity • Criterion validity • validity related to an outcome • concurrent validity (Does it relate to other variables the way the theory says it should?) • Example (Does the SAT relate to Achievement Tests? IQ?) • predictive validity (Does it predict something related to the construct?) • Examples (Does the SAT predict first-year college GPA? Does the SAT predict GRE scores? Does it “postdict” HS class rank?)

  7. Types of Validity • Discriminant validity • Does the measure fail to relate to measures of other constructs? • Examples (Does the SAT relate to measures of SES or self-esteem?)

  8. Types of Validity • Construct validity • Does the measure really measure the construct it says it does? • Is the construct (and its operational definition) appropriate for the research? • Examples (Does the SAT measure college potential? Is this an appropriate measure for college potential?)

  9. Old-fashioned Racism • Old-fashioned racism is the overt, blatant expression of racist attitudes • It’s easy to measure - ask questions like • “are you racist?” • “do you like African-Americans?” • “would you want African-Americans to attend the same schools as your children?” • scale has what type of validity?

  10. Old-fashioned Racism (cont.) • Problems with “old-fashioned racism”, • didn’t relate to subsequent voting behavior (what type of validity lacking?) • people were not reporting that they were racist anymore • 80% of White Americans were reporting that they were not racist at all (Dovidio & Gaertner, 1991) • Where do we go from here?

  11. Validation of a Measure • Subtle measure of racism • Use of political attitudes rather than direct inquiry (not quite the same thing!) • Modern Racism Scale (McConahay, Hardee, & Batts, 1981) • How much do you agree that: • “over the past few years, Blacks have gotten more economically than they deserve”? • “discrimination against Blacks is no longer a problem in the United States”?

  12. Validation of a Measure (cont.) • MRS needed to show that it was reliable and valid • How could it show that it was reliable? • How could it show that it was valid?

  13. Modern Racism Scale INTERNAL CONSISTENCY RELIABILITY (Homogeneity) RELIABILITY ANALYSIS - SCALE (ALPHA) N of Cases = 183.0 Reliability Coefficients N of Items = 7 Alpha = .7834 SPLIT-HALF RELIABILITY (Consistency) RELIABILITY ANALYSIS - SCALE (SPLIT) N of Cases = 183.0 Reliability Coefficients N of Items = 7 Correlation between forms = .5993 Unequal-length Spearman-Brown = .7525 4 Items in part 1 / 3 Items in part 2

  14. Validation of a Measure (cont.) • Validity of MRS • Face validity? • Survey says...

  15. MRS FACE VALIDITY

  16. Validation of a Measure (cont.) • Validity of MRS • Face validity? • Survey says... • Criterion validity? • Concurrent validity? • Predictive validity? • McConahay (1983) - tell me about it...

  17. Validation of a Measure (cont.) • Validity of MRS • Face validity? • Survey says... • Criterion validity? • Concurrent validity? • Predictive validity? • McConahay (1983) - tell me about it... • Discriminant validity?

  18. Validation of a Measure (cont.) • Validity of MRS • Construct validity? • Since its creation, the MRS has been probably the most widely used measure of racism in psychology • What do you think about its continued validity?

  19. McConahay -- Major Result

  20. Construct Validity -- Your Data and Civil Unions • How does the Attitudes to Civil Union scale do? • No reliability info, but similar scales work well • Face validity? • Concurrent validity? Correlation with MRS? • Discriminant validity? Correlation with Soc Desirability • CONSTRUCT • which sex more “tolerant”? • which political party? • which type of hometown? • Related to weight? Height? GPA?

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