Fixed Effects Least Squares
Posted: Thu Apr 26, 2012 4:55 pm
I'm working on a project where I analyze the impact of the change in per capita income on gubernatorial and presidential election results from 1970 to 2004. Because it's panel data, I'm using a fixed effects least squares model, where each year and each county has its own dummy variable. The problem is that there are roughly 3000 counties in the United States.
My equation is as follows:
Vote_percentage_by_county = αIncumbency + βper_capita_change*incumbency +County Fixed Effects + Year Fixed Effects.
I get a near singular matrix error, that the regressors may be perfectly collinear if I use more than 7 of the 9 year dummy variables. I get the same error when trying to include N-1 (N=number of counties) of the county level dummy variables.
I'm not sure what to do to fix this. Any help would be very much appreciated.
My equation is as follows:
Vote_percentage_by_county = αIncumbency + βper_capita_change*incumbency +County Fixed Effects + Year Fixed Effects.
I get a near singular matrix error, that the regressors may be perfectly collinear if I use more than 7 of the 9 year dummy variables. I get the same error when trying to include N-1 (N=number of counties) of the county level dummy variables.
I'm not sure what to do to fix this. Any help would be very much appreciated.