# NCA error in report

**URL:** <https://discourse.pumas.ai/t/nca-error-in-report/1287>\
**Category:** NCA\
**Created:** [September 30, 2025, 4:50pm UTC](https://discourse.pumas.ai/t/nca-error-in-report/1287 "2025-09-30T16:50:45Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![nmatharoo](https://avatars.discourse-cdn.com/v4/letter/n/919ad9/32.png) [@nmatharoo](https://discourse.pumas.ai/u/nmatharoo)\
**Post date:** [September 30, 2025, 4:50pm UTC](https://discourse.pumas.ai/t/nca-error-in-report/1287/1 "2025-09-30T16:50:45Z")

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Hello,

When I generate the report for NCA, the NCA calculations are shifted (red line to calculate kel) and is not on the observed points (black dots). How do I fix this?

Adding pictures below for reference.

Thank you in advance!

old version of pumas:

[![{1A29664A-DEEC-4380-AFA0-27948F00DD86}](https://yyz2.discourse-cdn.com/flex030/images/transparent.png)](https://canada1.discourse-cdn.com/flex027/uploads/umbphmx/original/2X/3/3707e271e276a1c4a5544c38da16ea58dfb21f8c.jpeg "{1A29664A-DEEC-4380-AFA0-27948F00DD86}")

[{1A29664A-DEEC-4380-AFA0-27948F00DD86}1071×584 64.2 KB](https://canada1.discourse-cdn.com/flex027/uploads/umbphmx/original/2X/3/3707e271e276a1c4a5544c38da16ea58dfb21f8c.jpeg "{1A29664A-DEEC-4380-AFA0-27948F00DD86}")

new version of pumas:

[![{B3B9A402-BC52-4FEE-9553-98ECCD6FEC36}](https://yyz2.discourse-cdn.com/flex030/images/transparent.png)](https://canada1.discourse-cdn.com/flex027/uploads/umbphmx/original/2X/a/a16be94390ac04130d30637d7a20543f62cb042b.png "{B3B9A402-BC52-4FEE-9553-98ECCD6FEC36}")

[{B3B9A402-BC52-4FEE-9553-98ECCD6FEC36}1107×683 49.8 KB](https://canada1.discourse-cdn.com/flex027/uploads/umbphmx/original/2X/a/a16be94390ac04130d30637d7a20543f62cb042b.png "{B3B9A402-BC52-4FEE-9553-98ECCD6FEC36}")

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**Author:** ![julius](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@julius](https://discourse.pumas.ai/u/julius)\
**Post date:** [October 9, 2025, 7:48am UTC](https://discourse.pumas.ai/t/nca-error-in-report/1287/2 "2025-10-09T07:48:52Z")

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Hello Namrata,

thank you for your bug report, this is indeed a regression that was introduced in a refactor of the backend, the reason is inconsistent handling of time. One trace uses time-after-dose and the other absolute time.

In an ongoing rework of the NCA.jl package, we are shifting to using time-after-dose everywhere which removes this whole class of time-based bugs. Until then, you can do the transformation to time-after-dose manually by subtracting the dose time from each profile’s time vector. This should get rid of the undesired offset in the plots.

Best,

Julius