How to Make a Universe Selection Step in Advance

Traders and quants often make mistakes when determining their universe like just not doing it at all so that's the biggest one. Not having a step that defines what am I willing to consider in my model is another common mistake. A factor can mean one of two things usually it can mean an alpha factor which is what Jess has been talking about with kind of a stock selection model. An alpha factor is any way that you assign a score to each stock at you know regular intervals and that score is supposed to be representative of which stocks you would like to own more or less. Risk factors are literally just a return string it's a time series of returns and we'll talk about that after we