What kind of statistics to use? - (Jun/26/2011 )

Hi,
I would like to ask for some advice with how to statistically analyze my data.
I have 3 specimens from 25 patients taken at the beginning of their disease, when they clinically improve and at the time of release from hospital. In all three specimens I measured the expression of gene of interest. Now I want to know whether there is a sex-deppendent difference in the disease course represented by differences in gene of interest expression. In other words, I would like to analyze differences among times of sampling in male and female patients.
The only way how I am able to do that is to count median (non-Normal distribution) for all three sampling times for men and women and compare these 3 and 3 median values by Mann-Whitney statistics. But this is too simplified I guess and I am loosing much of variability in each group. What would be the proper way to statistically compare my data?

Thank you in advance for any suggestion.
Paja

Try using ANOVA with 'sex' and 'disease state' as factors. As there is not equal number of men and women you can either discard extra samples and perform two-way ANOVA or check out ANOVA with unbalanced design.

ANOVA is only for normally distributed populations - don't use it for your analysis unless you can prove or assume normality in the distribution. You probably want the Kruskal-Wallace test (non-parametric equivalent of the ANOVA) with some sort of post-hoc testing.

for post-hoc use a wilcoxson test