So, I will run an email campaign and I want to calculate the difference between the current NPS score and the one after the campaign, to see if the campaign is actually making any impact at all. By the way, the sample sizes are going to be different. So my question is, what statistic calculation can I use for this?
Additional details, the score is ranked from 1 to 10. The sample sizes are different sizes, around 30 and 100. The hypothesis is that the testing of the sample averages are statistically different.