Correlation of the residuals

CFA Level II Quant
#1

Testing for the Conditional Heteroskedasticity and Serial Correlation appears to involve correlation of the residuals. Does anybody know what I have to regress these residuals against in order to derive that residual correlation?

Thanks

#2

Testing for Heteroskedasticity, the BP test requires a regression of the Squared Residual (Yi-Ŷ1)2 on the independent variable(X) Decision Rule Heteroskedasticity exists: If X explains the variation in the squared residual. Heteroskedasticity doesn’t exist:X doesn’t explain the variation. BP test for Heteroskedasticity: χ2= nR2 Someone please correct me if I am wrong.