creating a categorical variable with a continuous variable

#1
Hi,

I have a year of birth variable that I'm regrouping into categories (for example 1970-1974 is coded as 1, 1975-1979 is coded as 2, etc). I then want to use this variable as an independent variable in a regression model, would it be better to use it as a continuous variable (since the order of the codes have a chronological meaning) or as a categorical variable (with dummy variables for each category)?
 

hlsmith

Omega Contributor
#2
If you are determined to categorize years into blocks; I would make sure each block has the same number of years and I would treat the first group as the reference with it entered as a categorical variable. You can also create estimate statements to get a trend estimate across categories.