I am trying to optimize our AdWords ads and running some statistical tests. I use Chi-squared and Fisher's exact test for conversion rate data. Like for example the CTR or the click-to-conversion ratio.

But what if I wanted to run stats for COST per conversion. Is it a statistical abomination to run for example a Chi-squared using the number of euros spent instead of the number of clicks?

Example problem

Ad1: 300€ spent for 5 conversions = 60€ per conversion

Ad2: 500€ spent for 5 conversions = 100€ per conversion

  Is the difference significant?

Thanks for any help you can provide!

I am trying to optimize our AdWords ads and running some statistical tests. I use a chi-squared test and Fisher's exact test for conversion rate data; for example the click-through-rate (CTR) or the click-to-conversion ratio.

But what if I wanted to run stats for cost per conversion. Is it a statistical abomination to run, for example, a chi-squared test using the number of euros spent instead of the number of clicks?

Example problem

Ad 1 saw 300€ spent for 5 conversions (60€ per conversion). Ad 2 saw 500€ spent for 5 conversions (100€ per conversion). Is the difference between the two ads' cost per conversion statistically significant?