I was working the results of a regression equation and I wanted to test to see if there was significant heteroskedasticity in the residuals. Checking the results of the graph of fitted values versus residuals using
plot() produced a straight line that is almost exactly zero for most of the resulting graph and the data fits rather closely.
However, a studentized Breusch-Pagan test of the residuals using the
bptest() function indicated significant heteroskedasticity (BP = 8.4085, df = 1, p = 0.0037). I can't figure out why the Breusch-Pagan test is returning significant heteroskedasticity. The regression doesn't look heteroskedastic, the regression line is pretty consistent overall but there are a few outliers in the right half of the graph. There isn't a clearly non-linear pattern like increasing variance in residuals with increasing fitted values like one would expect from heteroskedastic results. So then why is the Breush-Pagan test telling me that I have significant heteroskedasticity in my regression?