# Interpretation of the ANCOM plots
**URL:** https://forum.qiime2.org/t/interpretation-of-the-ancom-plots/27240
**Category:** User Support
**Tags:** ancom
**Created:** [July 28, 2023, 6:22pm UTC](https://forum.qiime2.org/t/interpretation-of-the-ancom-plots/27240 "2023-07-28T18:22:52Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Cori](https://forum.qiime2.org/u/Cori)
#### Post date: [July 28, 2023, 6:22pm UTC](https://forum.qiime2.org/t/interpretation-of-the-ancom-plots/27240/1 "2023-07-28T18:22:52Z")
Hi,
Could you please help us with the following questions:
i) What does W represent? (I looked up the meaning of W and could not find a clear explanation).
ii) How are W and clr calculated, step-by-step (not the formula)?
iii) How can we "convert" W into a p-val or padj-val (q-val) type of measure?
iv) Can p-values be added to qiime composition ancom?
We would like to know how we can interpret it in a manner similar to volcano plots.
(running Qiime 2023.2 installed though conda).
Thank you for creating and maintaining such a critical resource !
Best,
Cori
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### Author:  [@colinbrislawn](https://forum.qiime2.org/u/colinbrislawn)
#### Post date: [July 29, 2023, 1:51am UTC](https://forum.qiime2.org/t/interpretation-of-the-ancom-plots/27240/2 "2023-07-29T01:51:05Z")
Hello Cori,
Welcome to the forums! :qiime2:
[ANCOM W value explained with step-by-step calculation](https://forum.qiime2.org/t/specify-w-cutoff-for-anacom/1844/10)
The W vs CLR plot is _already_ a volcano plot, just without the color coding and explicit thresholds. You can [make it look like a volcano plot using R](https://forum.qiime2.org/t/adjusted-analysis-ancom/11134/4).
> [@Cori](#):
>
> iv) Can p-values be added to qiime composition ancom?
If you run ANCOM directly in R, [adjusted p-values](https://www.bioconductor.org/packages/release/bioc/vignettes/ANCOMBC/inst/doc/ANCOMBC.html#p-values) are included in the `out$res` **res** ults data frame. These are not included in the Qiime2 output.
* * *
These questions are foundational to the ANCOM method. It may be worth revising the details of the original ANCOM-BC paper:
> **[Analysis of compositions of microbiomes with bias correction](https://pmc.ncbi.nlm.nih.gov/articles/PMC7360769/)**
>
> Differential abundance (DA) analysis of microbiome data continues to be a challenging problem due to the complexity of the data. In this article we define the notion of “sampling fraction” and demonstrate a major hurdle in performing DA analysis of...
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### Author:  [@system](https://forum.qiime2.org/u/system)
#### Post date: [August 29, 2023, 7:51am UTC](https://forum.qiime2.org/t/interpretation-of-the-ancom-plots/27240/3 "2023-08-29T07:51:10Z")
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