I have a sales data for brand1 (it has to be my dependent variable) and for brand2, brand3 and brand4. All of them are presented for 5 different chains. Data for every of chain is presented for each week from 1 to 117. It looks like presented below:
I have 585 rows. How can I build my model to explain brand1 sale? How can I deal with chain and weeks data? I thought about presenting chain data as dummy variables, but what in this case I should do with weeks?