I'm trying to measure the effect of an in-store media campaign on the sales. I have sales data along the time for test (treated) stores and control (not treated) stores.
Before comparing test and control, I have to rule out the price change and promotional factor for both time series. The decomposition of the time series into trend, seasonality and residual cannot isolate price or promotion effect.
My question is: how to model the price change component and remove it from the sales time series?