# Quality Plot Confusion

**URL:** https://forum.qiime2.org/t/quality-plot-confusion/29490
**Category:** User Support
**Tags:** truncate, quality
**Created:** [March 6, 2024, 6:32am UTC](https://forum.qiime2.org/t/quality-plot-confusion/29490 "2024-03-06T06:32:25Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![Nadine\_Veasley](https://forum.qiime2.org/user_avatar/forum.qiime2.org/nadine_veasley/32/17904_2.png) [@Nadine\_Veasley](https://forum.qiime2.org/u/Nadine_Veasley)
#### Post date: [March 6, 2024, 6:32am UTC](https://forum.qiime2.org/t/quality-plot-confusion/29490/1 "2024-03-06T06:32:25Z")

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Hi! I had went to view my demux.qzv file and this is the quality plot that I was given. I haven't seen one that looks like this before. I was wondering if it looked ok and where it would be plausible to truncate since there doesn't seem to be a clear point where all of the data starts to lose quality. I have attached the image below. Thank you in advance!

 ![Screenshot 2024-03-05 at 8.41.27 PM](https://forum-qiime2-org.s3.dualstack.us-west-2.amazonaws.com/original/3X/5/a/5a80b60ca765050bca3f508ad9ca2e2ae73235e6.png)

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### Author: ![buzic](https://forum.qiime2.org/user_avatar/forum.qiime2.org/buzic/32/16494_2.png) [@buzic](https://forum.qiime2.org/u/buzic)
#### Post date: [March 6, 2024, 8:50am UTC](https://forum.qiime2.org/t/quality-plot-confusion/29490/2 "2024-03-06T08:50:37Z")

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Hi @Nadine_Veasley 😃 👋

What kind of sequencing platform is your data from? My first guess is this is the result of binned quality scores from the Novaseq or Nextseq.

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### Author: ![Nadine\_Veasley](https://forum.qiime2.org/user_avatar/forum.qiime2.org/nadine_veasley/32/17904_2.png) [@Nadine\_Veasley](https://forum.qiime2.org/u/Nadine_Veasley)
#### Post date: [March 7, 2024, 4:06am UTC](https://forum.qiime2.org/t/quality-plot-confusion/29490/3 "2024-03-07T04:06:09Z")

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Yes, the samples weresequenced in a NovaSeq 6000 SP lane with 2x250nt and produced ~ 1 billion reads.

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### Author: ![buzic](https://forum.qiime2.org/user_avatar/forum.qiime2.org/buzic/32/16494_2.png) [@buzic](https://forum.qiime2.org/u/buzic)
#### Post date: [March 7, 2024, 8:56am UTC](https://forum.qiime2.org/t/quality-plot-confusion/29490/4 "2024-03-07T08:56:29Z")

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HI again @Nadine_Veasley ,

I believe you have your answer 😃. These plots are due to the sequencing platform you used, they give binned quality scores - so the quality plot looks different.

Try searching the forum (it's an amazing resource if you tap into it!) . There are many posts on the forum about moving forward with this data, like this [one](https://forum.qiime2.org/t/novaseq-and-dada2-incompatibility/25865/12).

best,

Vic

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### Author: ![system](https://forum-qiime2-org.s3.dualstack.us-west-2.amazonaws.com/original/3X/2/1/21af5fe23cb6f4579467c66a9ed94e55274ca7bd.svg) [@system](https://forum.qiime2.org/u/system)
#### Post date: [April 7, 2024, 2:56pm UTC](https://forum.qiime2.org/t/quality-plot-confusion/29490/5 "2024-04-07T14:56:36Z")

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