Thanks in advance for looking at my query. I have a very basic question regarding regression. We have to analyze a residual Plot by hand.

We do this in three steps. The third step I don't understand.

1. Divide in half from zero across and the overall points above and below the line should be close

2. Divide into 3 vertical regions check for spreadness/outliers in each section.

3. "In each of the 3 vertical regions the number of points below and above zero are close so it is OK"--This is the answer, but I am not sure what is meant. Does anyone have any ideas?

Also, when we analyze the residual plot the best outcome is that there is No pattern correct? What is the significance of the residual plot having no pattern?

What would a pattern signify?

Thank you in advance.