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How to setting contrast matrix for testing umbrella shape #204
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Hi Nemo, Thanks for your inquiry. ANCOM-BC2 pattern analysis is able to identify potential patterns by testing the contrast: where For instance, in this example, we want to identify taxa that are monotonically increasing across three groups, To test the monotonically increasing trend: We are essentially testing: Thus, we shall specify the contrast matrix The first row of Similarly, to test for the monotonically decreasing trend:
Lastly, to test for an umbrella trend: We shall specify the contrast matrix For testing monotonic trends (increasing or decreasing), one should specify the Best, |
Hi Huang, Thank you for your detailed information, now I know how to setting contrast matrix of umbrella shape. You can close this issue now. Thank you and bests regards, |
Hi,
Thank you very much for devoloping ANCOMBC2, it is a wonderful package. Although here you have uploaded detailed tutorial in Github and Bioconductor, I still have some question about contrast matrix setting in trend test.
I‘m working on a microbiota dataset with three groups (A, B, C), each group has 30+ samples. Now I want to find some microbiota taxons which have specific pattern in these groups using trend test of ANCOMBC. It is easy for detecting taxon which have monotonic trendency (increasing or decreasing) between these three groups, because it have detailed code in example. but for testing umbrella shape (convex and concave), i didn't find any example for setting contrast matrix.
Here is a code i want to test convex umbrella shape. If B is reference, I need to test B>A and B>C
matrix(c(-1, 0, -1, 1),nrow = 2, byrow = TRUE)
and settingnode = 1
Is it right? Could you kindly give me some advice for testing umbrella shape if this code is not right?
Thanks,
Nemo
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