Have you ever been on a client call where you have proudly presented your data and gave what you thought was an insightful recommendation? Only to find out that your data was based on wrong suppositions. If you have, you must understand how uncomfortable the situation is. Starting conditions Recently, I set out to determine the best options for Retail Pre-VIP and VIP flows for one of our clients. In order to do that, I used the segmentation features available in the client’s ESP (Email Service Provider for those who are not in the marketing business). As there are three separate lists, out of which two are retail lists and one is wholesale, I needed to focus only on the two Retail ones. One of the conditions I originally set up was that the customer belongs to one of the two Retail lists. Then, I determined the average customer values in order to get a baseline I could use for comparison. The next steps included further segmenting and fine-tuning until I