OT 575 - research methods part 8

what type of statistical test is repeated measures ANOVA?

parametric test

when is repeated measures ANOVA used?

- samples are correlated

- values of the dependent variable are normally distributed

- dependent variable is measured using a continuous scale

which test of variance is used in repeated measures ANOVA?

F test

how does the F test for repeated measures ANOVA differ from other types of parametric tests?

F distribution is always positive; it is always one-sided (unlike t-tests)

what is sphericity?

the variances of the differences between all pairs of groups are equal

what is the assumption if Mauchly's Test of Sphericity is not significant (p > .05)?

sphericity is met

if Mauchly's Test of Sphericity is met (p > .05), what is the next step (in SPSS)?

use repeated measures ANOVA with sphericity assumed

what is the assumption if Mauchly's Test of Sphericity is significant (p < .05)?

sphericity is not met; variances are different

if Mauchly's Test of Sphericity is not met (p < .05), what is the next step (in SPSS)?

use the Greenhouse Geisser correction

what is the Greenhouse Geisser correction?

adjusts the degrees of freedom so that the test is not biased

what does repeated measures ANOVA indicate?

indicates that time points are different (does not indicate where the differences lie)

how do we determine where the differences lie (after completing repeated measures ANOVA)?

by running a contrast analysis

how can type I error be controlled when completing a simple constrat?

divide the alpha level (.05) by the number of comparisons

what type of statistical test is the Friedman Test?

nonparametric test

when is the Friedman Test used?

- dependent variable is measured by an ordinal scale

- dependent variable was not normally distributed