Heteroskedasticity Residual Plots

I am attaching three different residual plots. I am trying to determine whether heteroskedasticity is present. I don't believe I see any pattern indicative of heteroskedasticity (nonconstant variance). I know it can be difficult to detect - do you see any indication of this?

© SolutionLibrary Inc. solutionlibary.com 9836dcf9d7 https://solutionlibrary.com/statistics/descriptive-statistics/heteroskedasticity-residual-plots-21h

Solution Preview

... all other lag values should be statistically "cero". That is, all other values should fall within Bartlett's band of significance. Now if you have a non-cero value, then a periodic component on your residuals sequence is present and you should be worrying about non-stationary conditions on your original data, maybe periodicities. A final word should be pointed to ...