What test to use?


New Member

We have measurements of presence of certain mycotoxines divided into where they were found, a) blood plasma and b) urine. For this, we measured i) presence or not and ii) concentration in ppb

Now we wish to check if there is a significant difference in a) present or not and b) average concentration between plasma and urine

Data is as follows: for each of the 9 substances, 151 measurements in plasma and 144 in urine (not the same persons)

What tests to use? I felt that we could do t-tests for the average concentrations in the two groups (N=9 for both), and t-test for the difference in proportions (again N=9), but I am having second thoughts. Does the fact that values are aggregates of lots of measurements within each category lead to other tests being more suitable?