Hi all,
I'm relatively new to Stata and I was wondering if anyone could potentially help with a problem I'm encountering. I'm attempting to model crime rates on a number of explanatory variables (inequality, median income, poverty, unemployment, population density, young males, ethnic minorities, prison population and police force strength). The data I am using is panel data, for ten different cities over a ten year period, and I am estimating my model using a pooled OLS.
I have carried out the regression itself, but I am currently going through standard robustness tests by investigating whether my coefficients hold up when I include dummy variables for each year I have covered in the data however I am encountering an apparent problem of collinearity.
When I add these dummies (using the command i.Year), I have the last year in my sample omitted due to collinearity.
I have no idea as to why this may be the case, but I'm keen to know if there's a way around this or ideas as to what may be the cause?
I have attached some photos for reference.
Thanks for any replies in advance!
I'm relatively new to Stata and I was wondering if anyone could potentially help with a problem I'm encountering. I'm attempting to model crime rates on a number of explanatory variables (inequality, median income, poverty, unemployment, population density, young males, ethnic minorities, prison population and police force strength). The data I am using is panel data, for ten different cities over a ten year period, and I am estimating my model using a pooled OLS.
I have carried out the regression itself, but I am currently going through standard robustness tests by investigating whether my coefficients hold up when I include dummy variables for each year I have covered in the data however I am encountering an apparent problem of collinearity.
When I add these dummies (using the command i.Year), I have the last year in my sample omitted due to collinearity.
I have no idea as to why this may be the case, but I'm keen to know if there's a way around this or ideas as to what may be the cause?
I have attached some photos for reference.
Thanks for any replies in advance!
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