Serial Correlation means (loosely speaking) that error in time period 2 is correlated with error in time period 1. In these videos, we look at what is serial correlation and when does it arise? What are different orders of serial correlation? What are the consequences of ignoring serial correlation? How do you detect first order serial correlation?
Serial (Auto) Correlation introduction
Serial (Auto) correlation of first order
Consequences of ignoring serial (Auto) correlation
Durbin Watson test
LM Test for first order serial (Auto) correlation