I have to examine historical sales data in order to figure out which calendar events have an influence. I would like to ask for some feedback if it makes sense or what I could do better.
What I have:
- Historical daily sales data of the last last five years
Here is my plan (so far):
- Take every year and transform it into a seasonal adjusted time series. (Not sure yet which of the two methods I should use: X-12-ARIMA or TRAMO/SEATS)
- When I subtract the seasonal adjusted graph of a year from the raw data of that year I get a graph consisting of "seasonality + calendar effects", right?
- After I have done 1. and 2. for each year I should have 5 graphs which I can compare. Is there any way I can divide calendar effects and seasonality?
I would like to figure out for example what influence Christmas, Chinese new year or Easter has on the sales.