Would hugely appreciate a little guidance
So I have a cohort of 35 patients and I have a measurement of chemical at artery (A) and vein (V).
The chemical is present in both serum and red blood cells with different distributions. Normal distribution in RBC and non-gaussian in serum.
If I analyse serum and RBC separately the difference from A to V is significant in the RBC and non-significant in the serum
I want to compare the totals RBC+Serum from A to V.
My question is as follows, How do I do it!!
If I add RBC and serum for each individual the population has non-gaussian distribution, using a paired analysis such as the wilcoxin test shows they are significantly different.
However, is this the correct approach? Or should I be performing some other multiple comparison test of both serum, RBC and total (for A and V) and assuming non -gaussian distribution for the whole analysis??
As you might be able to tell, I am by no means a statistical expert!!
Thank you for your help
Phillip
To compare the totals of your chemical in RBC+Serum (between A and V), the distribution of the chemical in the single compartments (RBC and Serum) is irrelevant. What is relevant is only the total concentration and its distribution.
Being a concentration measure I would assume that it has some kind of gamma- or log-normal distribution, so that it would be sensible to analyze the mean difference between the log-transformed values.
Hi,
Maybe, in your study it's possible to use the Hoteeling-T- square
http://www.real-statistics.com/multivariate-statistics/hotellings-t-square-statistic/hotellings-t-square-independent-samples/
I advice you, dear Phillip, to practice ethical research. All hypothesis of infinite population has an idea principle but does not have guarantized its objectivity because they are uncheckable hipothesis in practice.
I recommend you this book in Spanish.
Ruiz Espejo, M. (2014). Ethical Research and Biostatistics (2nd edn). Lulu Press. Raleigh, NC.
http://www.lulu.com/shop/mariano-ruiz-espejo/investigaci%C3%B3n-%C3%A9tica-y-bioestad%C3%ADstica/paperback/product-21822728.html
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