How did you do a t test on total sales when there are only two values, one for each group?

Paul R. Swank, Ph.D. Professor, Developmental Pediatrics Medical School UT Health Science Center at Houston

-----Original Message----- From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of Lu Liu Sent: Tuesday, June 07, 2005 9:54 AM To: SAS-L@LISTSERV.UGA.EDU Subject: A stat question

I have a stats rather than SAS question, but I think many SAS experts can help on this. Thank you very much in advance. We did an A/B test to test effectiveness of 2 e-mail creatives. The results are below:

Group Order AOS Sales A 62 $243 $15,000 B 92 $239 $22,000

* AOS stands for average order size ** Sales = AOS x Order

After I applied t-test, it shows that Group B placed significantly more orders than Group B, but the average order size (total sales divided by total orders) and total sales are not significantly different. I have 2 questions,

1) Is the total sales not significantly different because average order size between the 2 groups is not significantly different?

2) Is it correct to conclude that group B has generated (92 - 62) * $239 = $ 7,170 incremental sales since Group B's total orders are significantly different from Group A?

Your help is greatly appreciated.

Thank you, Lu