I've got a question about statistics. I have an experiment in which X - is a length of DNA fragment and for each X, there are 4 measurements of Y. Suppose, it is not obvious that there is an increase of Y with X. What is the proper statistic to verify that this increase is not a fluke?
P.S. I have many experiments like that so the answer will be useful. I don't think a simple correlation will do since the measurements are not independent: there are 4 replicates for each X. Also averaging is not good since this way I would lose a lot of stat power.