Well, forecasting the past is a pointless exercise, I assume.
I am restudying statistics, restarting from scratch.
The first time I did it? Few times in school and at the beginning of the university, of course.
Why now? Because I want to understand and review the computations behind some existing models, instead of re-inventing the wheel- with my old models, I needed to understand but not to write computations.
The main difference? Models built on historical data and limited behavioural analysis, vs. models built on historical behaviour and limited data.