Let's say I have some data on the amount of money spent on tv ads and total revenue from all sales. The data is available for three separate month.
Jan Feb March $ spent on tv ads 100 110 150 total sales revenue 1000 1000 1500
The problem I am trying to solve is whether the marketing campaign (tv ads) had a significant effect on total sales revenue.
Now, I'm still not sure on how to proceed in terms of tests, either time series analysis, etc. (suggestions?) But one other issue is going to occur, and that regards whether or not to pool the data. Should I run separate tests for each month or do I pool the data together?
So my question is: When is it appropriate to pool data for analysis?