ANCOM results: ASV with W values of 0 identified as differentially abundant

Hi everyone,
I tried to use ANCOM to identify the biomarker at ASV level.
There were lots of ASV did be indentified as diffrentially abunant, like piture below:

But the w value are very low even =0
Can I use those ASV as biomarker? Below is my volcano results.

Thanks a lot!

Good morning,

But the w value are very low even =0

You may have found this already, but if not, check out this thread on ANCOM (1) and low W values:

Also check out the ANCOM-BC plugin for Qiime2:

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Thanks for your detailed reply.
I tried both rarefied and unrarefied table. The results are similar but not identically same.

Do you have any recommendation on which one is more reliable? I am a little bit confusing because I read a previous reply stated that the results derived from unrarefied and rarefied table supposed to be same. Thanks a lot!

ANCOM is designed to be used on unrarefied data. (It does the normalization itself!)

We would not expect rarefied and raw data to be identical, as rarefaction throws away data to get the same counts per sample. However, big trends should be the same regardless of normalization.

Got it! Thank you so much!

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