The sawdust has settled and you have data on both of your testing groups. This chi-squared test allows you to calculate whether or not the difference in your response rates is statistically significant. If your results don’t pass the chi-square rigmarole, then you shouldn’t make any assumptions about a winner or loser in your test. And you know what they say about ASS-U-ME-ING… Run the test again with a larger sample, or pick a new variable to experiment with.​

Please provide what was observed: