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SP_08_Variables_T-tests__ANOVA

33 t tests comparison t df p no effects independent

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Unformatted text preview: p Significant effects Independent samples t-tests 0.55 Pretest 3.24 Posttest Paired t-tests Control Program 49 49 49 49 .85 .01 .95 .01 High t-score Low p-value 0.25 3.33 Looking at it another way... How to write it? Independent ttests in Table 3 suggest that the groups are not statistically different from zero at pretest t(49) = .55, p = .85 (two tailed) but are significantly different at post test t(49) = 3.24, p = .01 (two tailed). Moreover, paired ttests, also presented in Table 3 suggest that ADHD symptoms significantly declined in the program group t(49) = 3.33, p = .01 (two tailed), but not in the control group t(49) = .25, p = .95 (two tailed). Summary Between subjects yes Within subjects no #indep variables 1 #levels test 2 Indep. T-test no yes 1 2 Paired T-test A wrinkle... REMEMBER: Can only look at 2 levels at a time So if you have 3 time points, can't do all of them at once (have to look at 2 of the 3 in any one ttest) So if you have 3 groups, can only look at 2 groups in any one ttest Scenario #1 Add more measurement occasions (more posttests) 80 75 70 65 60 55 50 45 40 35 30 Pretest Posttest1 Posttest2 Comparison Program Scenario #1 What kind of design is this? What would you have to do to Table 3 How many paired t-tests? How many independent samples t-tests? 80 75 70 65 60 55 50 45 40 35 30 Pretest Posttest1 Posttest2 Comparison Program Scenario #1 What would you have to do to Table 3 How many paired ttests = 6 How many independent samples ttests? = 3 Group...
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