How do I select a link function?

[Porkins]

In ASM in states that in the glm package there are five link functions that can be used with the binomial distribution. Is this just common knowledge? How do I know which link functions go with which family?

 

If i type ?glm it tells me their default link but does not tell me all possible options.

If I type ?make.link it tells me there are 9 different links i can use but not which family they should go with.

 

 

[SamCastillo]

Excellent question.

Here’s a video explanation.

There are two components that you need to take into consideration: the range of the response distribution and the range of the mean. Once the SOA’s modules are released in a few weeks, you will be able to review the chapters that cover this. By going through several examples of past exams, you can see why they justify each choice.  Almost every sitting of PA has included a GLM question. You also need to consider the interpretation – does it need to be easy to understand? What’s the canonical link function?

If you enroll now you can get access to more than 28 hours of video tutorials. You can practice on realistic exams and then get feedback in real time. There are a number of lessons that cover these topics and in addition to the SOA’s answers, we also provide alternative answers.  There are often multiple correct ways of answering these questions as long as you can justify your reasons, which our examples cover.

Best,

Sam Castillo

Course Instructor at ExamPA.net

[Author]

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