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Discrepancy with stratified incidence estimates

Dear all,

My team is carrying out incidence estimation in ATLAS and a question has come up regarding a discrepancy with the person-years for the incidence estimates. The person-time for the stratified estimates do not sum perfectly to the person-time for the overall incidence, and these numbers are far enough off that rounding cannot explain the discrepancies. For example, the overall person-years for one incidence was 516 years; whereas, for males it was 310 years and 216 years for females (total = 526 years). Is there an explanation for this difference? We see this across many of our incidence analyses.

Thank you very much for your help!

Defintely looks like a bug, but what is surprising to me is that the individual subgroups should be calculating time at risk in exactlyt he same way, just with a subset of the population. So it’s very odd that the N and cases sum up between Males and females to the overall total but the TAR does not. Should be running the same code except on a different subset of data. Strange! I will take a look at this.

Can you confirm which version of WebAPI/Atlas you are running?

Thank you for the report.


Thank you so much Chris! We are running version 2.7.3.


There has been updates to the incidence rate calculation that is in the 2.8 release:

You may want to try to update.

Edit, yes, this is the issue that is describing your problem:

Thank you Chris! We will update to the newest release.