I have panel data with a time-invariant variable across firms. However, when I tested the xtsum after setting the panel data, there was very little (8.66e-17) within variance. I checked over and over in the data, but it was invariant within every firm over the time period of 2005-2014.
How do I deal with this? Is there a way to see which observation is causing this variance, if I had missed any? If not, how can I explain this variance in the test results?