Hello everyone I would like if possible to ask a question regarding a part of the statistical analysis in my MSc project:

Following the sampling of the inlet and outlet of a stormwater pond at different times for different types of phytoplankton

I wish to make comparisons of time same sampling spot at the different dates ( for example Inlet 1 compared to Inlet 2) as well as the difference between inlet and outlet on the same sampling date ( like Inlet 1 with Outlet 1).

So far I have come to the conclusion that the data are very skewed so I likely need to use non-parametric tests.

So far I have tried the following using minitab:

Wilcoxon test and Mann-Whitney tests comparing the pairs above, However I keep getting P values which are over 0.05 despite the what is in my opinion a large variation between the sample data.

I have also tried transforming the data in various ways like ranking and logarithms with no success

Could it be that the tests I am performing are not appropriate for this type of data?

I would be extremely grateful if someone with more experience in statistical tests could help me find if I am just analyzing them wrong or not

Following the sampling of the inlet and outlet of a stormwater pond at different times for different types of phytoplankton

I wish to make comparisons of time same sampling spot at the different dates ( for example Inlet 1 compared to Inlet 2) as well as the difference between inlet and outlet on the same sampling date ( like Inlet 1 with Outlet 1).

So far I have come to the conclusion that the data are very skewed so I likely need to use non-parametric tests.

So far I have tried the following using minitab:

Wilcoxon test and Mann-Whitney tests comparing the pairs above, However I keep getting P values which are over 0.05 despite the what is in my opinion a large variation between the sample data.

I have also tried transforming the data in various ways like ranking and logarithms with no success

Could it be that the tests I am performing are not appropriate for this type of data?

I would be extremely grateful if someone with more experience in statistical tests could help me find if I am just analyzing them wrong or not

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