one factor repeated lec 3 Flashcards
what is a one way repeated measures design
everyone takes part in the conditions
how is this allocated and why
randomly to get rid of error effects
what does repeated measures help with
allows us to compare individuals scores with their own in another,
what analysis i used for repeated measures
one way repeated ANOVA
if significant what happens next and why
a Bonferroni corrected post hoc to see how they differ
what are the advantages of repeated measures
more efficient (quicker and cheaper) and increased statistical power (greater likelihood to detect an effect)
what are the disadvantages of repeated measures
carry-over effects (exposure) and order effects (tire/improve)
how is order effects counterballenced
randomisation of the order
what are the disadvantages of one way repeated measures ANOVA
sphericity
what is sphericity
the variance of different scores should be roughly equal
how do you test if sphericity has been violated
mauchleys test of sphericity
what is mauchleys test of sphericity
tests the null if all the variances are equal
what do we want from mauchleys test of sphericity
non sig (P>0.05) as this means the variances are equal
when is sphericity not a problem
when there is only one factor with two levels as only have one difference scorew
what if sphericity is violated
cant trust the results, more likely to produce a type error
how is a violation of sphericity dealt with
greenhouse geisser correction row
what is the pre-test post-test design
measure the before, expose, then measure after (change over time)
when is a pretest-posttest necessary
if one way ANOVA is significant and post hoc test is done
what are the limitations of pretest-posttest
measuring this DV repeatedly people improve through practice, and we can’t avoid order effects through randomisation of time as we always followed by pre-test
what overcomes the limitations of pretest-posttest
measure a DV that won’t change due to practice such as heart rate
how isa pretest posttest carried out
bonferroni corrected post hocs on the relevant pairs
