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

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    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.

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    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.
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    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.
    "Very few theories have been abandoned because they were found to be invalid on the basis of empirical evidence...." Spanos, 1995

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

    Quote Originally Posted by noetsi View Post
    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...
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    noetsi (04-22-2013)

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    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).
    "Very few theories have been abandoned because they were found to be invalid on the basis of empirical evidence...." Spanos, 1995

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