Dear R-helper,

Please suggest some methods for my question below.
We measured the amount of protein A in patient blood in pre-treatment and
post-treatment condition from 32 patients.
--------------------------------------------
           Pre-treatment      Post-treatment
Pat1         25                         28
Pat2         19                         15
Pat3         94                         89
...
Pat32       49                         23
------------------------------------------------
How can we prove that the treatment did not make any difference in the
amount of protein A. In another word, Pre- and post- are the same.
1) I assume that a paired t-test can work, but can I prove a null hypothesis
by not-rejecting it?
2) If I use correlation test, the best I can get is to reject a null
hypothesis that is the correlation is 0. This seems not good enough to say
treatment does not make difference. Will it be good enough by adding a Rho
value?
3) Will regression work by showing the estimate of Beta is 1?

If I have multivariate results: not only protein A, but we also tested
protein B, protein C... and total 25 different proteins for each patient in
pre- and post-conditions. How can I summary if pre- and post condition makes
difference?

Thank you so much!

Xiang

	[[alternative HTML version deleted]]

