# different histograms despite same analysis for two different batches
**URL:** https://forum.qiime2.org/t/different-histograms-despite-same-analysis-for-two-different-batches/18308
**Category:** User Support
**Tags:** demux, paired-end
**Created:** [January 31, 2021, 7:20am UTC](https://forum.qiime2.org/t/different-histograms-despite-same-analysis-for-two-different-batches/18308 "2021-01-31T07:20:44Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@tinabui04](https://forum.qiime2.org/u/tinabui04)
#### Post date: [January 31, 2021, 7:20am UTC](https://forum.qiime2.org/t/different-histograms-despite-same-analysis-for-two-different-batches/18308/1 "2021-01-31T07:20:44Z")
I created a sequence manifest and am demultiplexing. There are two batches of sequences (batch A and B). I'm doing quality control on them separately and then merging them later. However, after demultiplexing each batch, the histograms in the qzv file looks different despite using the same code for each (see code below). Batch A has a single histogram but Batch B has two histograms describing forward and reverse reads with the same exact numbers. Why does this occur? [paired-end-demux\_A.qzv](https://forum.qiime2.org/uploads/short-url/jU2osWvICprVy9jhtX7x1fEc17J.qzv) (294.1 KB) [paired-end-demux\_B.qzv](https://forum.qiime2.org/uploads/short-url/6B0OUp5ThskLLZKsGOnfmN0mXTU.qzv) (315.6 KB)
%%time
!qiime tools import
--type 'SampleData[PairedEndSequencesWithQuality]'
--input-path seqSampleManifest\_A
--input-format PairedEndFastqManifestPhred33V2
--output-path paired-end-demux\_A.qza \
---
### Author:  [@Nicholas\_Bokulich](https://forum.qiime2.org/u/Nicholas_Bokulich)
#### Post date: [January 31, 2021, 10:39am UTC](https://forum.qiime2.org/t/different-histograms-despite-same-analysis-for-two-different-batches/18308/2 "2021-01-31T10:39:48Z")
Hi @tinabui04!
Judging from the provenance in your visualizations, you used two different versions of QIIME 2 at two different times — one visualization was generated with 2020.2, and the other with 2020.8.
It looks like several adjustments were made to the visualizer in that time to add support for reverse reads etc, so **the difference in appearance is just related to these changes**. These changes are mentioned in the release notes, though they are not too specific, but this is a good way to generally see what changed, e.g.:
> [@QIIME 2 2020.6 is now available!](https://forum.qiime2.org/t/qiime-2-2020-6-is-now-available/15537):
>
> The QIIME 2 2020.6 release is now available! Thanks to everyone involved for their hard work! As a reminder, our next planned QIIME 2 release is scheduled for August 2020 (QIIME 2 2020.8), but please stay tuned for updates. Check out the [QIIME 2 2020.6 docs](https://docs.qiime2.org/2020.6/) for details on installing the latest QIIME 2 release, as well as tutorials and other resources. Get in touch on the QIIME 2 Forum if you run into any issues! Virtual machine builds will be available sometime within the next week - watch th…
> [@tinabui04](#):
>
> Batch B has two histograms describing forward and reverse reads with the same exact numbers.
That's the distribution of per-sample read counts for each direction. The fact that they match is a good thing! It's exactly what you want to see — paired-end reads should match in their paired samples.
Good luck!
---
### Author:  [@system](https://forum.qiime2.org/u/system)
#### Post date: [March 3, 2021, 4:39pm UTC](https://forum.qiime2.org/t/different-histograms-despite-same-analysis-for-two-different-batches/18308/3 "2021-03-03T16:39:50Z")
This topic was automatically closed 31 days after the last reply. New replies are no longer allowed.