Model comparison in mean-dispersion trend in DESeq2
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Loïc • 0
@e387433b
Last seen 11 months ago
Canada

I would like to have a systematic procedure, when choosing model of mean-dispersion trend in DESeq2 when using estimateDispersions() function. I know that 4 different models are available with strong impact on trend estimation. However, in many cases, "goodness-of-fit" cannot be achieve only with graphical analysis but we need something more systematic. So, my question is: "Does it exist any procedure to compare models when choosing different fitType in estimateDispersions()?". I am not aware of some likelihood or deviance returned by DESeq2 in order to proceed to model comparison.

Any insights will be appreciated.

Loïc

DESeq2 StatisticalMethod • 950 views
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@mikelove
Last seen 4 hours ago
United States

There is an automated procedure in that if the parametric fit does not converge, then a more flexible local regression is used.

The algorithm and its convergence is described in the Dispersion Trend section of the Methods of the 2014 paper.

But we don’t have anything like GoF for the trend. Note also in this section of the paper our discussion of estimation when mu < 1/alpha. If you really want to focus on the trend in the range it is estimable, I would filter low count genes (eg average counts < 10).

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Thanks Michael Love ! Ok so let's summarize for my own understanding. If I want to proceed to some model comparison of the trend, fitting the models by my own only considering genes with average counts > 10 should be reasonable ? For giving you a little bit of context, in the lab where I work, people are interested in systematic model comparison. Since I am only a statistician I try to find a reasonable approach to do so.

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Yes, if you see that part in the paper, we argue that when average count is less than 1/alpha then you have little information for estimation of dispersion. alpha could be .1 or even .01 so if you really wanted to be safe, filter at a higher average count, like 100.

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I will go through the paper one more time just to be sure I got the point. Thanks for your help !

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