2 Way ANOVA or multiple t tests with correction?

[jfar18]

Hi all,

I am trying to do some data analysis, and I'm not sure whether to use a 2 way ANOVA or multiple t tests with Bonferroni correction.

I am looking at the effect of a chemical on bacterial binding to different polymers. So for each polymer, I want to know if there is a difference in binding between the treatment group and the control group.

I initially wanted to do a 2 way ANOVA with multiple comparisons because I have two independent variables (polymer and treatment group) and one dependent variable (bacterial binding). However, would multiple t tests with correction be more appropriate if I am only comparing each polymer +/- treatment, and not comparing the polymers to each other?

I really hope a 2 way ANOVA with multiple comparisons is ok for this data, because I have spent a LONG time making all my figures using the ANOVA data....

Thanks in advance for you input!!!

 

[noetsi]

Why would you not compare the impact of the polymer on the DV? I can't see any advantage if that is an IV.

In general ANOVA is recommended to multiple t test, although I have not seen anyone do what you are.

 

[jfar18]

Thanks for your response!

I do want to look at the impact of the polymer, but I only want to compare each polymer to itself +/- treatment, not to the other polymers. So the experimental design is "for each polymer, is there a difference in binding +/- treatment?" I am not looking to see if the binding differs between polymers.

 

[noetsi]

It seems then that you are in practice running one predictor (treatment)within each "group" (the specific polymer). That is one regression for each polymer. In that case ANOVA and single t test should generate identical results - its your choice which you use.

 

[rogojel]

hi,
I think you would not need the Bonferroni correction in this case, though this is an interesting question.

regards