Editing Observational error (section)

===Sources of random error{{anchor|Random}}===
The random or stochastic error in a measurement is the error that is random from one measurement to the next. Stochastic errors tend to be [[normal distribution|normally distributed]] when the stochastic error is the sum of many independent random errors because of the [[central limit theorem]]. Stochastic errors added to a regression equation account for the variation in ''Y'' that cannot be explained by the included ''X''s.