Hi all

I am using GraphPad Prism 6. I am assaying steroid hormones with a receptor and am struggling to choose the correct statistical test to determine significance. Based on previously published data a one way ANOVA would be best for what I am doing. My experiment consists of a number of steroids I have assayed with a receptor, each independent of the other. One steroid response is 10x greater than all the other steroid responses (let's call this steroid, steroid A). I would like to graph all my data on the same axis and compare whether each steroid response is significantly enhanced compared to my basal response. I have selected a One way ANOVA with a multiple comparison's test (comparing each column to my control, basal) with a Tukey's posthoc test (I have also tried the Fischer's LSD as to not correct for multiple comparison's). When I include steroid A on the graph nothing is significantly different to my basal reading besides steroid A but as soon as Steroid A is removed everything else becomes significant. This seems incorrect to me as this means there is dependence between each response and each comparison to the control should in actual fact be independent to the remaining responses. Is this therefore the incorrect test and which test should I then use? Or if this is correct, why should the bar for steroid A be effecting the statistical analysis of my remaining steroids?

Any help or explanations would be greatly appreciated!