Suppose for each visitor to your site, whether the visitor sees the ad is determined randomly. After the month is completed, you have the following information:
Mean sales when ad was shown: $26.75
Standard deviation of sales when ad was shown: $18.21
Number of times ad was shown: 8,172
Mean sales when ad was not shown: $27.21
Standard deviation of sales when ad was not shown: $19.20
Number of time ad was not shown: 10,437
Does showing the ad affect your sales? Explain your reasoning.
Using the data from above, the advertiser claims there is evidence that running the ads may actually improve your sales. Is there evidence for this? Explain your reasoning, why or why not.