The current additive noise term is purely positive, that is, no negative noise terms are included. The small change makes it so that the noise has negative and positive values. This would make the noise scatter plot about the actual linear model look a bit more natural.
The current additive noise term is purely positive, that is, no negative noise terms are included. The small change makes it so that the noise has negative and positive values. This would make the noise scatter plot about the actual linear model look a bit more natural.