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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Tags: clodds statement, confidence intervals, confint(), logistic regression, MASS library, ods system, proc logistic, profile likelihood, SAS formats

Posted in SAS | Comments Off on 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...

Read more »

Tags: clodds statement, confidence intervals, confint(), logistic regression, MASS library, ods system, proc logistic, profile likelihood, SAS formats

Posted in SAS | Comments Off on 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...

Read more »

Tags: clodds statement, confidence intervals, confint(), logistic regression, MASS library, ods system, proc logistic, profile likelihood, SAS formats

Posted in SAS | Comments Off on Example 9.14: confidence intervals for logistic regression models

The yearly US News best college ranking is an important tool in comparing schools for students and their eager parents. The latest data is publicly available (paying 20 bucks would get full access) . And the methodology is easy to find and expla...

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Tags: data preparation, PROC GLMSELECT, proc logistic, PROC PLS, web analytics

Posted in SAS | Comments Off on Some analysis on university ranking by US News

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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Tags: elrm package, events/trials syntax, exact logistic regression, exact statement, proc logistic

Posted in SAS | Comments Off on Example 8.16: Exact 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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Tags: exact logistic regression, Firth logistic regression, Firth option, logistf package, logistic regression, proc logistic

Posted in SAS | Comments Off on Example 8.15: Firth logistic regression

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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Tags: Design package, glm() function, goodness of fit, Hosmer and Lemeshow, le Cessie and Houwelingen, logistic regression, proc logistic

Posted in SAS | Comments Off on Example 8.7: Hosmer and Lemeshow goodness-of-fit