# covariance and SE calculation without convergence

**URL:** <https://forum.certara.com/t/covariance-and-se-calculation-without-convergence/2368>\
**Category:** Modelling and Simulation\
**Created:** [February 14, 2012, 6:22am UTC](https://forum.certara.com/t/covariance-and-se-calculation-without-convergence/2368 "2012-02-14T06:22:16Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![dora\_teo](https://avatars.discourse-cdn.com/v4/letter/d/7ea924/32.png) [@dora\_teo](https://forum.certara.com/u/dora_teo)\
**Post date:** [February 14, 2012, 6:22am UTC](https://forum.certara.com/t/covariance-and-se-calculation-without-convergence/2368/1 "2012-02-14T06:22:16Z")

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Hi, I noticed that sometimes I get a successful covariance step, with reported parameter SE and CV%, but in a model that actually failed to converge. I know that in NONMEM, the $COV step requires a successful convergence. Could you explain these differences between Phoenix and NONMEM? Thank you, Dora