# Thread: Statistical test of difference among values from multiple timepoints

1. ## Statistical test of difference among values from multiple timepoints

Hello,

I have a question on selecting a statistical test.

I am trying to assess changing abundance of microbes in oral cavity along time. My goal is to distinguish statistically significant difference and classify the microbes into different response groups(e.g. positive responders, negative responders...etc).

There are two oral samples: samples with dietary treatment of interest and oral samples with no treatment. I measured the relative abundances of microbes in oral samples at multiple time points: 2,4,6,8 days for samples with treatment and 0, 8 days for samples with no treatment(control). 0 day samples are measured before treatment effect takes place, so it is basically the same for both treated groups and control groups. Each has 3 replicates, thus there are 3 replicates*(0 day for both groups+8day for control+2,4,6,8 day time points for treated groups)= 18 samples total.

Do you have any suggestion for analysing these data? I am thinking about calculating the difference of abundance between each time point and the 0 day samples and then doing statistical tests on these delta values. Replicates from different time points are all independent because all samples are measured destructively from different individuals. Thus I am planning to calculate delta between every possible combination of nonzero-day replicates and three different replicates of the 0 day samples. However, I am having difficulty choosing statistical tests. Initially I considered 2-way ANOVA but I am unsure if it is the appropriate way to do it.

Thanks!

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