I'm running an A/B test to see if the improved website layout increases revenue. First, I would like to check if the sizes of the control and experiment groups are statistically different. I have data on the number of users visiting the site per day within 29 days. Below I will insert the data from the first 5 days: Day Control Visits Experiment Visits 1 1764 1850 2 1541 1590 3 1457 1515 4 1587 1541 5 1606 1643 It seems to me that I should use the t- or z-test to achieve my goal, but so far I have used them to test statistical difference between population means, not their sizes. P.S. This is the first question I asked on stackexchange. Any suggestions or tips on how I can improve the question will be welcomed.