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Matched Pairs t Tests SPSS. Source of the Data. Cognitive-behavioral intervention to reduce African American adolescents' risk for HIV infection Group EC was given a standard 2-hour educational program Group BST went through an 8 week behavioral skills training program.
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Source of the Data • Cognitive-behavioral intervention to reduce African American adolescents' risk for HIV infection • Group EC was given a standard 2-hour educational program • Group BST went through an 8 week behavioral skills training program.
The Dependent Variables • The log-transformed frequency of condom-protected sexual intercourse • Measured before the intervention, at posttest (8 weeks later), 6 weeks after posttest, and 12 weeks after posttest.
Download the Data • http://core.ecu.edu/psyc/wuenschk/SPSS/MAN_1W2B.sav • Bring the data into SPSS • We want to do two matched pairs t tests • One for the EC group • One for the BST group
Split the File by Group • Data, Split File
Conduct the Test • Analyze, Compare Means, Paired Samples T Test, Pretest versus fu6
Obtain Estimates of Cohen’s d • Download the .sav and .sps files • D-EqN-- Estimate Cohen's d, equal n data (including correlated samples) • d-EqN-Doc-- instructions • d-EqN-Dat-- necessary data file • d-EqN-Run-- syntax file
Summary Statement, BST • Adolescents in the behavioral skills training group (n = 20) engaged in significantly more condom-protected intercourse six weeks after the training (M = 18.80, s = 11.04) than prior to the training (M = 13.45, s = 13.77), t(19) = 2.35, p = .030, d = .43.
Summary Statement, EC • Adolescents in the educational control group (n = 20) engaged in significantly less condom-protected intercourse at the six week followup (M = 8.60, s = 11.09) than at pretest (M = 19.8, s = 21.87), t(19) = 2.40, p = .027, d = .65.