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PSY6010: Statistics, Psychometrics and Research Design

PSY6010: Statistics, Psychometrics and Research Design. Professor Leora Lawton Spring 2007 Wednesdays 7-10 PM Room 204. Reliability Test for Scales - Cronbach’s Alpha.

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PSY6010: Statistics, Psychometrics and Research Design

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  1. PSY6010: Statistics, Psychometrics and Research Design Professor Leora Lawton Spring 2007 Wednesdays 7-10 PM Room 204

  2. Reliability Test for Scales - Cronbach’s Alpha Another data reduction technique, but useful when they aren’t factors (different sets of attitudes) but rather, measures of different facets of the same attitudes, as measured by a Likert Scale. • GUI: Analyze – Scale – Reliability Analysis • Add Likert scale items into menu window. Model = alpha • For Statistics, click on Scale, Scale if item deleted, and Means. • Drop out any for whom, when deleted, increase the Cronbach’s alpha score. • Create variable which is a sum of the Likert values, e.g., compute newvar = var1 + var2 + var3.

  3. Experimental Design Analyses OLS Regression – behavioral modeling • tests for relationships between the DV and IV, and if a time component is included, can examine causality. It’s good for understanding behavior or attitudes or functioning. • Other methods are more about predicting group membership, or determine group differences. The latter question is pertinent for experimental design research. Experimental Design Methods: Looking for Group Differences • Logistic: Change versus no Change following intervention. • Z-tests (for proportions) on outcome variable, or T-tests (for means), or testing for differences between two groups (e.g., control/test). See Handout. • Go to website: http://www.dimensionresearch.com/resources/calculators/ttest.html • ANOVA, ANCOVA, or MANOVA or MANCOVA (see text 4th edition, pg 27 Table 2.1).

  4. One Dependent Variable – Analyses of variance and covariance A. One-Way ANOVA: for example, assessment score for group 1 without training versus group 2 with training. • DV is one continuous or interval variable. • IV is one categorical variable • GUI: Analyze – Compare Means – One-Way Anova

  5. Multivariate Analyses of Variance • For SPSS, use from GLM for anova-like models that feature more than a bivariate test, that is, look at multivariate tests (hence the M in Manova or Mancova for multiple dependent variables), and Factorial ANOVA and ANCOVA address multiple IVs.. . • GUI: Analyze Generalized Linear Model Univariate (for singular dependent variable) Multivariate (for 2 or more dependent variables) • Factorial ANOVA or t-test • DV is one continuous or interval variable. • IV is one categorical variable (your critical group identifier), but multiple covariates allowed. • ANCOVA: For example, single DV (continuous) and continuous IVs. • And so forth…

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