I have two time-series of 2 different products
x & y. They belong to the same main category, e.g.: Iphone 6 and Iphone 5. Maybe one product is the predecessor of the other product.
I tested for correlation between the sales of the 2 products and got
r=.67. Correlation is calculated on the number of sales of the 2 products for the same month. Does this mean that there is a causal relationsship between the sales of the two products?
Are both sales pattern the same? In this case I might be able to forecast one time series with the historical data of the other one.