The analysis of time series is important to try to predict the future.

A time series has usually a tendency and a sazonality.

We can have additive models

Y = T + S + C + e

Or multiplicative models

Y= T * S * C * e

Where T – Tendency, S – Sazonality, C – Cyclical, e – error

 

The analysis of errors allows to determine which model is a better fit to that particular time series.