Posts Tagged ‘ proc logistic ’

Example 9.14: confidence intervals for logistic regression models

November 15, 2011
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Example 9.14: confidence intervals for logistic regression models

Recently a student asked about the difference between confint() and confint.default() functions, both available in the MASS library to calculate confidence intervals from logistic regression models. The following example demonstrates that they yield d...

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Example 8.16: Exact logistic regression

November 30, 2010
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Example 8.16: Exact logistic regression

In example 8.15, on Firth logistic regression, we mentioned alternative approaches to separation troubles. Here we demonstrate exact logistic regression. The code for this appears in the book (section 4.1.2) but we don't show an example of it there. ...

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Example 8.15: Firth logistic regression

November 22, 2010
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Example 8.15: Firth logistic regression

In logistic regression, when the outcome has low (or high) prevalence, or when there are several interacted categorical predictors, it can happen that for some combination of the predictors, all the observations have the same event status. A similar e...

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Example 8.7: Hosmer and Lemeshow goodness-of-fit

September 28, 2010
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Example 8.7: Hosmer and Lemeshow goodness-of-fit

The Hosmer and Lemeshow goodness of fit (GOF) test is a way to assess whether there is evidence for lack of fit in a logistic regression model. Simply put, the test compares the expected and observed number of events in bins defined by the predicted p...

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