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

Dependent Variables: Continuous Psychometric Properties Validity Reliability

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

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

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

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)

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

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

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

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

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 .

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

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

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.

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

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.

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

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

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

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

Instruments Description of Measure Validity Estimates Instrument name Convergent/Discriminate Validity Acronym Validation Sample(s) Authors Key References Reliability Estimates Brief description of construct(s) Chronbach’s alpha coefficient Type of measure (e.g self-report) Previous and Current studies Number of items Test/Re-Test Example of items Items response options Factors or subscales Scoring options and direction