I'm analysing weekly sales data for a product which is highly seasonal. I would like to capture the seasonality in the regression model. I have read that if you have quarterly or monthly data, in that case you can create 3 and 11 dummy variables respectively — but can I deal deal with weekly data?
I have nearly 3 years of weekly data. The independent variables are average price, advertising spend, promotions, a couple of competitive indexes, school.holidays (1/0), temperature and others. The dependent variable is sales of that product. I am not looking for a time series model as I am using a multiple regression model and I'm trying to understand the influence of the independent variables and not making any forecast.