Which test to use?

#1
Hi folks!
Can someone give me some advice on what test to use?
I did a medical experiment and I look for the right statistical test. My sample size is very small, though.
I want to compare two groups with unequal sample numbers (Group A n13, Group B n26).
I measured the percentage of a certain protein on the cell surface in % in a Group before and a group after treatment.
Now I'm looking for the right test to compare differences. It's obvious there is a big difference as percentages in group B are
much smaller after treatment but I need to come up with statistics for it.
Can someone give me a good hint?
THANK YOU!
Sinclair
 

Karabiner

TS Contributor
#2
So you have n=39 cases, each case has 2 characteristics, "group" (A vs. B) and "protein on surface" (yes versus no)?
The association between these characteristics can be analysed using Chi² test or probably Fisher's exact test (the
latter can be used if assumptions of the Chi² regarding expected frequencies in the cells of the table aren't met).

With kind regards

Karabiner