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Class 9 Dependent Variables, Instructions/Literature Review

Class 9 Dependent Variables, Instructions/Literature Review. Chapters 13, 22 Corkin , & P&B 7 – SP 13. Dependent Variables: Continuous. Psychometric Properties Validity Reliability. Validity. Convergent and Discriminate Validity Correlation Predictive Validity

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Class 9 Dependent Variables, Instructions/Literature Review

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  1. Class 9Dependent Variables, Instructions/Literature Review Chapters 13, 22 Corkin, & P&B 7 – SP 13

  2. Dependent Variables: Continuous • Psychometric Properties • Validity • Reliability

  3. Validity Convergent and Discriminate Validity Correlation Predictive Validity Correlation- Differences across groups Longitudinal Construct Validity Factor structure-latent constructs

  4. Reliability The extent to which scores show true variance in attributes across participants as opposed to error variance Assumption: Error variance is random, therefore it does not correlate with anything More items of good quality = higher reliability One item scales have very low reliability; around r =.25

  5. Types of Measures • Observational Measures • Self-Report Paper-and-Pencil Measures • Content tests- right/wrong answers • Likert-scales

  6. Sources of Measurement Error Specific error something unique about the instrument/observational task that differs from what the researcher intended (e.g. social desirability; reading level; idioms) Transient error some temporary factor that affects the measurement (e.g. order of instruments; historical events; noise while observations occur; tiredness)

  7. Sources of Measurement Error Scoring/Recording error Tend to be random (self-report/raters) Inter-rater disagreement/observer drift in observation studies, what initially may appear as antisocial behavior may later be judged more normative

  8. Types of Reliability • Inter-Scorer • Test / Re-test • Alternate Forms • Internal Consistency • how items correlate with each other

  9. Internal Consistency Reliability • Split-Half • Kuder-Richardson • Dichotomous items- right /wrong • Chronbach Alpha • Average correlation of all possible split-half reliabilities

  10. Parenting Skills Measure: Q 2a-c • 12-item measure rx= .70 to rx= .95 among White samples • Expected reliability estimates among the Latina sample • Three-item measure: rx=.40 to rx=.45

  11. Parenting Skills Measure: Q 2a • 12-item measure: internal consistency reliability coefficients rx= .70 to rx= .95 among White participants • 70% to 95% of variability in respondents’ scores is due to and the rest is due to .

  12. Reliability Estimates: Q 2a Extent to which variability is due to true variation versus error Cronbach alpha =. 70; 70% of variation in scores is due to true differences in parenting skills & 30% is due to error Cronbach alpha =. 95; 95% of variation in scores is due to true differences in parenting skills & 5% is due to error

  13. Parenting Skills Measure: Q 2b • 12-item measure rx= .70 to rx= .95 among White samples • Expected reliability estimates among the Latina sample

  14. Parenting Skills Measure: Q 2b • 12-item measure rx= .70 to rx= .95 among White samples • Expected reliability coefficient among Latina sample =>.70 Yes/No ? Reliability refers to scores with specific and . It’s a property of not of instruments.

  15. Parenting Skills Measure: Q 2b • 12-item measure rx= .70 to rx= .95 among White samples • Expected reliability coefficient among Latina sample =>.70 No. Reliability refers to scores with specific respondents and conditions It’s a property of scores, not of instruments

  16. Parenting Skills Measure: Q 2c • 12-item measure rx= .70 to rx= .95 among White samples • Reliability estimates among the Latina sample • Three-item measure: rx=.40 to rx=.45. How to improve the scale scores’ reliability.

  17. Parenting Skills Measure: Q 2c • Three-item measure: rx=.40 to rx=.45 – New items increase reliability only if they are of good quality: validity and reliability

  18. Reliability and Correlation: Q 5 • In correlational research, how does the reliability of twoscoresaffect the probability that the observed correlation coefficient between the two scores approximates the “true” correlation coefficientof the constructs?

  19. Internal Reliability and Correlation Parenting Skills 1 PSM1 rx= .45 Parenting Skills 2 PSM2 rx = .90 Self-Esteem SE rx = .85 PSM1 (rx= .45) correl. Self Esteem PSM2 (rx= .90) correl. Self Esteem

  20. Reliability vs. Validity Observed correlation coefficient will be smaller and less accurate with the less reliable measure Correlations between constructs areattenuated by the reliability of the measures The reliability of a measure puts a ceiling on its validity

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