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

**URL:** https://forum.qiime2.org/t/ancom-results-asv-with-w-values-of-0-identified-as-differentially-abundant/25558
**Category:** User Support
**Created:** [February 20, 2023, 4:53pm UTC](https://forum.qiime2.org/t/ancom-results-asv-with-w-values-of-0-identified-as-differentially-abundant/25558 "2023-02-20T16:53:03Z")
**Posts on this page:** 1
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### Author: ![colinbrislawn](https://forum.qiime2.org/user_avatar/forum.qiime2.org/colinbrislawn/32/6221_2.png) [@colinbrislawn](https://forum.qiime2.org/u/colinbrislawn)
#### Post date: [February 20, 2023, 4:58pm UTC](https://forum.qiime2.org/t/ancom-results-asv-with-w-values-of-0-identified-as-differentially-abundant/25558/2 "2023-02-20T16:58:01Z")

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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:

> [@ANCOM: 'low W taxa identified as significant' issue's workaround, ANCOM2 code/instructions](https://forum.qiime2.org/t/ancom-low-w-taxa-identified-as-significant-issues-workaround-ancom2-code-instructions/6040):
>
> Hi folks, Some users (including myself) have noticed that in some cases ANCOM behaves oddly in that it identifies very low/0 W valued taxa as differentially abundant. See [here](https://forum.qiime2.org/t/ancom-error-reporting-all-taxa-as-significant/5401) and [here](https://forum.qiime2.org/t/ancom-giving-me-w-scores-of-0/5155/3) for example of this behavior. In contacting one of the developer's of ANCOM regarding this issue ,Dr. Peddada had the following explanation/recommendation. A potential reason for the problem is that the earlier code was trying to empirically derive the threshold for significance. When W takes on small values …

Also check out the ANCOM-BC plugin for Qiime2:  
[https://github.com/mortonjt/q2-ancombc](https://github.com/mortonjt/q2-ancombc)

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