# Questions about sample-classifier
**URL:** https://forum.qiime2.org/t/questions-about-sample-classifier/1591
**Category:** User Support
**Tags:** sample-classifier
**Created:** [October 23, 2017, 8:19pm UTC](https://forum.qiime2.org/t/questions-about-sample-classifier/1591 "2017-10-23T20:19:31Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@eDNA](https://forum.qiime2.org/u/eDNA)
#### Post date: [October 23, 2017, 8:19pm UTC](https://forum.qiime2.org/t/questions-about-sample-classifier/1591/1 "2017-10-23T20:19:31Z")
I have a few questions about sample-classifier
(1) I have run "qiime sample-classifier classify-samples", but do not understand the results. Could anybody help me interpret the results?
Here is my command:
qiime sample-classifier classify-samples
--i-table BI-feature-table-c10l60.qza
--m-metadata-file metadata4\_BI.tsv
--m-metadata-category distance
--output-dir BI-SML
I have run similar commands a few times for different feature tables and obtained different Accuracy Ratios. One result is attached. [visualization.qzv](https://cdck-file-uploads-global.s3.dualstack.us-west-2.amazonaws.com/flex002/uploads/qiime21/original/1X/dc2f668e68507f8ee869d338f205a0138e79f7c5.qzv) (261.9 KB)
(2) I also run maturity-index and regress-samples, but encountered errors.
qiime sample-classifier maturity-index
--i-table BI-feature-table-c10l60.qza
--m-metadata-file metadata4\_BI.tsv
--p-category distance
--p-group-by distance
--p-control D500
--output-dir BI-maturity-index
Plugin error from sample-classifier:
Cannot have number of splits n\_splits=5 greater than the number of
samples: 4.
qiime sample-classifier regress-samples
--i-table BI-feature-table-c10l60.qza
--m-metadata-file metadata4\_BI.tsv
--m-metadata-category distance
--output-dir BI-regress
Plugin error from sample-classifier:
could not convert string to float: 'D090'
For you information, there are 42 samples (7 distances X 6 samples/distance) in the feature table. The 7 distances are D000, D015, D030, D060, D090, D125 and D500.
Thanks.
---
### Author:  [@Nicholas\_Bokulich](https://forum.qiime2.org/u/Nicholas_Bokulich)
#### Post date: [October 24, 2017, 4:43pm UTC](https://forum.qiime2.org/t/questions-about-sample-classifier/1591/3 "2017-10-24T16:43:19Z")
Hi @eDNA,
Thank you for posting your questions.
> [@eDNA](#):
>
> have run “qiime sample-classifier classify-samples”, but do not understand the results. Could anybody help me interpret the results?
The description of the outputs is given in [the docs](https://docs.qiime2.org/2017.9/tutorials/sample-classifier/#predicting-categorical-sample-data) (scroll down below the command block). Basically, the heatmap (and confusion matrix table below it) is going to show the fraction of times that samples in each group were assigned the each group. See more details [here](https://en.wikipedia.org/wiki/Confusion_matrix).
> [@eDNA](#):
>
> I have run similar commands a few times for different feature tables and obtained different Accuracy Ratios.
That is absolutely normal — there are a number of random factors at play here, in subsampling training/test samples, in subsampling features, and in training the models. Small amounts of variation are normal and fine. You could supply a random number seed with `--p-random-state` to get replicable results.
> [@eDNA](#):
>
> I also run maturity-index and regress-samples, but encountered errors.
These methods are not appropriate for the data types that you are providing. Regression methods only accept numerical `--p-category` data, and the distance metadata column that you are providing is not numerical. If appropriate, you could convert these to numerical values (e.g., if 0, 15, 30, etc, indicate meters or some other units of distance from something).
Furthermore, it looks like `maturity-index` is inappropriate for the data you are using. I recommend reading over the [docs](https://docs.qiime2.org/2017.9/tutorials/sample-classifier/#maturity-index-prediction) and the original paper for the [maturity-index method](https://doi.org/10.1038/nature13421) to understand what this method measures. `category` and `group-by` should be different metadata columns; e.g., `category` will usually be a measure of time (distance might also work) and `group-by` should be, e.g., two different treatment groups that are measured at the same points described in `category`. This method will determine whether `group-by` groups experience different trajectories of change over change in `category`.
I hope that helps! Let us know if you have further questions.
---
### Author:  [@system](https://forum.qiime2.org/u/system)
#### Post date: [November 24, 2017, 10:47pm UTC](https://forum.qiime2.org/t/questions-about-sample-classifier/1591/5 "2017-11-24T22:47:01Z")
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