independent groups Flashcards
what do we test in independent groups
the difference between two sets of ordinal, interval or ratio data
what do independent tests tell us
whether the probability of finding this difference between two samples is small enough to reject the null hypothesis
what inferential test do we perform if both groups are parametric
parametric test
what inferential test do we perform if both groups are non-parametric
non-parametric test
what inferential test do we perform if one group is parametric and one is non-parametric
non-parametric
design for independent groups
between participants
what are independent group
two sets of data from two different groups on the same measure
which test do you use for independent groups
depends on the distributions
what do you need to describe the data if its parametric
mean & SD
what test is used for parametric independent data
t-test
what is a t-test used for
to compare the pooled variance of two unrelated groups of samples
whats the df for independent groups t-test
(no. of p’s group 1+ no. in group 2) - 2
how do you identify if the t-test is significant
compare the value to the t-test critical values table
when is the t-test significant
if t is greater than the critical value at .05
how to report t test in APA
(t(df) =xx.xx, p=.xxx)
what do you need to describe the data for a non-parametric independent groups test
median and IQR
what test is used for a non-parametric independent groups test
mann-whitney test
what does a mann-whitneey test test
whether the two independent samples were selected from populations that have the same distribution
what does mann-whitney test if the distributions are similar
how much the medians differ
what does a mann-whitney test is the distributions are different
how much do they differ
in a mann-whitney test what do you rank scores by
size from lowest to highest
what do we use instead of df for mann-whitney test
n
significance of U value - mann-whitney
we want U to be smaller that critical value
how to report mann-whitney U in APA format
U= xx.xx, p=
how do you rank scores in mann-whitney U
put rank order in next column
what is the number of ranks in a Mann-Whitney
how many different scores there are
whats the lowest score ranked at in Mann-Whitney
1
what are equal scores ranked as
the average rank for that score
what do you to to rank mann-whitney after the ranks have been calculated
sort data back into participant order using participant as the sort criterion
what do you do after the rank order has been completed in mann-whitney
add up the ranks for each group
how do you identify the U value
the lowest of the two rank scores
