I used codon based z test of selection to check selection pressure on a protein and i performed neutral test, positive test, and purifying test. Results of three different tests gave probability and static values which conflict with each other. I want to understand how to interpret results either statistically or biologically??
p statistic Neutral test 0.348 -0.942 Positive test 1 -0.979 Purifying test 0.161 -0.996
significance level = 0.05
Biologically i interpret that dn-ds (statistic) value is negative that means more synonyms changes so negative selection pressure. But if i look statistically every test has greater p value than 0.05 and z value is also in acceptance region for every test so on that basis every test hypothesis is accepted. that is very confusing. Please guide me if I am going in the right direction.