I'm comparing the results that I obtain when doing a DE analysis with the Wald test and the likelihood-ratio test. One the thing that I've noticed is that there are many genes with 'beta' close to zero that are considered differentially expressed between the conditions.

I know that the likelihood-ratio test does't use the beta values to calculate the p-values, but I find it strange that transcripts with similar expression values between the conditions are being considered differentially expressed.

Volcano plot (Wald test q-values): enter image description here

Volcano plot (likelihood-ratio test q-values): enter image description here

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    $\begingroup$ I’ve never used Sleuth but there are several odd things about this data as far as I’m concerned: the y-axis on the Wald test plot for instance seems way off (inflated). The q-values in the LR plot are a lot more reasonable. $\endgroup$ Commented Aug 15, 2017 at 17:17
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    $\begingroup$ Cross-posted on biostars and the kallisto mailing list. $\endgroup$
    – Devon Ryan
    Commented Aug 15, 2017 at 18:07
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    $\begingroup$ What does this look like if you plot Beta vs average TPM across all samples, excluding those with qval < 0.05? $\endgroup$
    – gringer
    Commented Aug 15, 2017 at 19:53
  • $\begingroup$ What is the actual question? Why are some genes with beta = 0 and qvalue < 0.05? $\endgroup$
    – llrs
    Commented Sep 16, 2017 at 11:39
  • $\begingroup$ Yes, that's the thing I can't understand $\endgroup$
    – elsoja
    Commented Sep 23, 2017 at 19:03

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    $\begingroup$ Could you post here also the solution to your problem? Just to avoid having to chase the anser from site to site $\endgroup$
    – llrs
    Commented Sep 26, 2017 at 9:14

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