Analysing Historical Data

Hi all,

We are in the process of switching to SAP APO statistical forecast tool and would like some input from experts please.

I am end user and I would like to know

1. How to analyse historical data i.e. Look for Trend, Seasonality etc
2. How to change parameters Alpha,Beta,Gamma and Sigma and how to understand what they are doing?
3. How to select best fit model?
4. Are there any resources in market giving above information with some real time examples?

Many thanks for your input

Abhi