How to Transform the Historical Data?

The data is not obviously useful in its raw form at for doing some forecasting. How well does the historical data tell the full story? Can you make accurate predictions on that alone, or do you have to tie in things like weather and holidays and sporting events? External data, in this case, especially for back sharing systems, plays a very important roll. There is definitely a good amount of work that needs to be done in finding the right sources of information.