# How to use regressors?

**URL:** <https://discourse.pumas.ai/t/how-to-use-regressors/803>\
**Category:** model-syntax\
**Created:** [December 5, 2022, 10:45am UTC](https://discourse.pumas.ai/t/how-to-use-regressors/803 "2022-12-05T10:45:32Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![pascalschulthess](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.pumas.ai/pascalschulthess/32/347_2.png) [@pascalschulthess](https://discourse.pumas.ai/u/pascalschulthess)\
**Post date:** [December 5, 2022, 10:45am UTC](https://discourse.pumas.ai/t/how-to-use-regressors/803/1 "2022-12-05T10:45:32Z")

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How do I make use of regressors? To be more specific:  
I have a dataset with PD measurements after a number of different doses described by the `:dosegrp` column. Now, I’m trying to set up a simple turnover model such as

```auto
ddt_E = kin*(1-Imax*Cc/(Cc+IC50)) - kout*E

```

where `Cc` is informed by the `:dosegrp` column.

In Monolix, for instance, I can define the column as regressor and then use `Cc = {use=regressor}` in the model file.

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**Author:** ![vijay](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.pumas.ai/vijay/32/96_2.png) [@vijay](https://discourse.pumas.ai/u/vijay)\
**Post date:** [December 5, 2022, 12:10pm UTC](https://discourse.pumas.ai/t/how-to-use-regressors/803/2 "2022-12-05T12:10:41Z")

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If `Cc` is part of your dataset, the bring in `Cc` as a covariate by specifying it in `read_pumas` and then in your `@covariates` block

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<div class="post-metadata">

**Author:** ![pascalschulthess](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.pumas.ai/pascalschulthess/32/347_2.png) [@pascalschulthess](https://discourse.pumas.ai/u/pascalschulthess)\
**Post date:** [December 5, 2022, 2:48pm UTC](https://discourse.pumas.ai/t/how-to-use-regressors/803/3 "2022-12-05T14:48:54Z")

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Thanks @vijay. Works great!