voomLmFit fitted log-CPM values
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Lina ▴ 10
@hakusen03-10599
Last seen 2 days ago
United States

Hello,

I'm running this code to get the fitted log-CPM values after running voomLmFit, but it doesn't work.

v <- voomLmFit(y, modsv, block = samples$clone, keep.EList = TRUE)
cpm.fit.tab <- cpm(v, normalized.lib.sizes=TRUE)
Error in min(y) : invalid 'type' (list) of argument

I suspect I get the error because CPM function works with DGEList. Looking at the output voomLmFit has EList. Does EList contain the fitted log-CPM values? If not, can you please recommend how to get the fitted log-CPM values from the object generated by voomLmFit?

Thanks,

limma edgeR • 111 views
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@gordon-smyth
Last seen 17 hours ago
WEHI, Melbourne, Australia

Fitted values are obtained from limma MArrayLM objects by

fitted(v)
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Is the output from fitted(v) in the log2 CPM scale? or CPM scale?

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The fitted values are on the log2CPM scale. I would have told you if they were not!

I think you may be getting confused by the differences between limma and edgeR. voomLmFit() produces a limma fitted model object so, if you use it, then you must use limma functions for the downstream analysis. In limma, expression is always on the log2-scale. If you want to use edgeR downstream functions such as cpm(), then use glmQLFit() instead of voomLmFit(). That will create an edgeR fitted model object instead a limma object.

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