Can't run Independent-Samples T-test

Hello, everyone,
I need a piece of your help on a popular question of Statistical Test Choosing :confused:

I have an Experimental Group and a Control Group
I have pre-test scores for both groups
the experimental group receives a treatment
I have Post-tests scores for both groups

my research question is whether the treatment has had any effect.

in my SPSS data I have separate variables for all the scores:
Control group Pre-test scores
Control group Post-test scores
Experimental group Pre-test scores
Experimental group Post-test scores

and the ID column. that's it,
so when i try to run the Independent-Samples T-test I have no Grouping variable... :(

Do I need to re-form my datasheet?
Do I need a different statistical test?

thanks in advance!
appreciate your help!!!


Less is more. Stay pure. Stay poor.
You should subtract the post values by the pre values, then run your test on the differences between the two groups.


TS Contributor
Do I need to re-form my datasheet?
Three columns, one for the group membership, one for
pretest and one for posttest scores. Possibly you can
then perform a repeated measures / mixed ANOVA with time
of measurement as within-subjects factor and group
membership as between-subject variable. The interaction
is what you are intersted in.

With kind regards