A retailer sells 8 brands across 500 locations. What statistical test can be used to determine if a recent uptick in year over year sales is significant?
You can use a hypothesis test, with your null hypothesis being there is no effect and your alternative hypothesis being there is an impact.
A hypothesis test is where you compare if the mean and standard deviation of one event is significantly greater or less than another. In this case, take a simple random sample of 30 locations calculating their means and standard deviations(use thirty so the results are normal) from each year.
You would next need to set an alpha level. This is the bar your p value (probability that the event happened at random chance) must pass in order for you to accept your alternative hypothesis and reject the null.
Lastly run the numbers through a calculator or computer program to determine if your resulting p value allows you to reject or accept your alternative hypothesis.