T-tests

What:

Ho: there is no difference between the means

H1: there is a difference between the means

When:

1. "Paired t-test" if: 2 repeated measures

SPSS:



























































































































Effect size: is the difference "clinically" significant?































































































































































Sample results section

"A paired t-test was conducted to assess if women perceived greater group than personal discrimination. Results indicated that women perceived significantly greater group (M = 6.32, SD = 2.06) than personal discrimination (M = 5.75, SD = 1.87), t(113) = 4.16, p = .01. While the mean difference appeared small, the effect size was acceptable, n2 = .133"



2. Independent groups t-test

What:

Ho: there is no difference between the means

H1: there is a difference between the means.

But, note the design difference!

































SPSS:





















































































































































































































































Sample Results section

"An independent groups t-test was performed to test the hypothesis that the type of discrimination portrayed would affect the amount of action taken. Results indicated that women exposed to the "stereotype" discrimination took less action (M = 2.95, SD = 3.48) than those exposed to the "social issue" discrimination (M = 4.34, SD = 3.72), t(111) = -1.40, p =.041. While the mean difference appeared large, the effect size was small, n2 = .037)."



ANOVA

What?

When?

SPSS

























































































































































































Sample Results section

"A one-way analysis of variance was conducted to evaluate the effect of type of discrimination on taking action. The independent variable, type of discrimination, included three levels: group discrimination, group and personal discrimination and no discrimination. The dependent variable was the amount of action taken. The ANOVA was significant, F (2, 253) = 12.93, p = .01, suggesting that type of discrimination had an effect on action. Post hoc tests showed that those who were exposed to no discrimination took less collective action (M =, SD) than those who were exposed to both group and personal discrimination (M =, SD=) and personal alone (M = SD=), ps = .01. There were no differences between those exposed to the group and personal discrimination together and those exposed to personal discrimination alone, p > .05.