I am trying to predict monthly sales by product based on a plethora of variables. There are 4 predictors. One is categorical (month) and the other three are numerical. One of the variables is just part sales.
The data I am trying to predict is nested — there are product groups and colors within each product group. I am trying to predict sales by color.
The data is cyclical (sales vary by month/season).
What model would you recommend using?