how does fitglm treat categorical variables?

Question

Hans van der Horn 2022-3-6

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1664629-how-does-fitglm-treat-categorical-variables

评论： Jeff Miller 2022-3-7

Dear all,

I'd like to verify something about categorical variables in fitglm. As input I use a table which also contains categorical variables (sex (0 vs 1), and education (on a scale 1 to 7). If I understand the documentation correctly, fitglm automatically treats these as categorical, and it also automatically dummy codes when necessary? (for education in this case). Is this correct?

Thanks very much.

Best

Hans van der Horn

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Jeff Miller 2022-3-6

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1664629-how-does-fitglm-treat-categorical-variables#answer_911404

在 MATLAB Online 中打开

I don't that is correct. WIth numerical values in the table, I think you have to mark the variables as categorical with something like:

tbl.sex = categorical(tbl.sex);
tbl.education = categorical(tbl.education);

Where there are three or more categories (e.g., education) you can check the df's to make sure that the variable has been treated as categorical (6 dfs) rather than numerical (1 df, essentially a regression slope across 1-7).

2 个评论
显示无隐藏无

Hans van der Horn 2022-3-7

Dear Jeff,

Thanks for your answer. I tried as you suggested and indeed it works better, with now dummy variables defined in the model.

Best Hans

Jeff Miller 2022-3-7

Hi Hans,

That sounds good. If this answer solves the problem that you were having, then please accept it using the "Accept" button (so that the question no longer appears to be open).

Jeff

请先登录，再进行评论。