I have several markets across the US where a marketing program was launched, and I want to compare the mean weekly unit sales before and after the launch. I'm using the 10-weeks prior to launch as my baseline and the 10 weeks post-launch as my result. Now at the end I will use a paired t-test to compare the change relative to the control markets (not in the program).
However my question is for the interim. Management wants to see updated results every week.
- Is it valid to recompute statistical significance each week while the program is still running?
- Which test is appropriate? The samples are linked so it should be a paired t-test, but that requires the same observations which I don't have until the end.