# Thread: Testing the assumption of linearity in a multi-level logistic regression analysis

1. ## Testing the assumption of linearity in a multi-level logistic regression analysis

Hello all!
I am working on a multi-level logistic regression (Binary Outcome) model and am trying to finding the best way to check the assumption of linearity for the continuous variables. I am using STATA and have tried lowess graphs using the logit option, Box-Tidwell, and the lincheck methods . All of these options have given somewhat conflicting results. Variables that appear to be linear using the lowess graphs are not considered linear according to Box-Tidwell or the lincheck methods. I know the lowess graphs are smoothed graphs so this maybe explains why they conflict. I am wondering what the most reliable or accepted method for checking linearity using STATA is. I am also familiar with SAS if someone knows a better method using that package.

Thanks

2. ## Re: Testing the assumption of linearity in a multi-level logistic regression analysis

How are you checking the linearity? Because the linearity assumption is on the logit of the true probability of success.

3. ## Re: Testing the assumption of linearity in a multi-level logistic regression analysis

There is no assumption of linearity between the raw data - only between the logit and IV.

I never realized that multilevel analysis could be used with logistic regression before - I thought it required an interval DV. That is useful to know.

4. ## Re: Testing the assumption of linearity in a multi-level logistic regression analysis

Originally Posted by noetsi
There is no assumption of linearity between the raw data - only between the logit and IV.

I never realized that multilevel analysis could be used with logistic regression before - I thought it required an interval DV. That is useful to know.
You can use it with any type of model you want. Estimation becomes more tedious but it's just a model...

5. ## The Following User Says Thank You to Dason For This Useful Post:

noetsi (04-22-2013)

6. ## Re: Testing the assumption of linearity in a multi-level logistic regression analysis

My multileval class focused exclusively on interval level DV. Should have realized it was not limited to that (although all the articles were I believe tied to interval level data too).

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