I am a vascular surgeon planning a research project.
I need some advice regarding the sample size calculation.
I am looking at the same group of patients pre and post-procedure looking for a change in the diameter of their main blood vessel at 2 different points.
We have some data...
I have a problem in calculating sample size. I did do a small pilot experiment, so this is some sample data with the same structure:
df <- data.frame(ID = c(1,2,3,4,5,6,7,8,9),
School = c("A","A","A","B","B","B","C","C","C"),
Nice to meet people do same things on the web:)
Here the question:
I have independent two group of patients
first group have 10 patients
second have 5 patients
can I compare their surgical corrections (advancement measured as milimeters) with ManWhitney test?