Tests for unmatched pre/post/follow-up data

Posted by Meddyg on Jun 29, 2021; 3:54pm
URL: http://spssx-discussion.165.s1.nabble.com/Tests-for-unmatched-pre-post-follow-up-data-tp5740605.html

Hi all,

I would like to ask for help with the most appropriate (if there is one) statistical test to apply to some data I have. I have had a look at this forum to see if a similar query has been answered before to no avail.

Simply, I have created a new lesson for students. There are around 100 students in total. I asked them to complete a test before the new lesson, then after the lesson and then finally around 6 months later to see if they still remembered the material from the lessons. Each student attempt was then scored.

The test was not compulsory and collected anonymous responses, so I have no way of matching any of the pre/post/follow up responses. Also because the test was voluntary, I have different numbers of participants in each group ranging from around 110 pre, 95, post and 70 in follow up. All I know is that all participants took part in the new lesson so they have all received the intervention in the post and follow up groups and none of them had attended the session prior to this.

All the statistical tests I have looked at which would be appropriate for three time points, either assume the participants are different or are participants with same numbers in each group whose responses can be matched.

Could anyone advise on the best way of analysing the data? Happy to follow up with more info as required.

Many thanks