When the Wall St. Journal writes about Judy, Jennifer, and Jasmine (not using the names, obviously), folks pay attention. Click here to read an article from November titled "Shopping's Great Age Divide".
If you're analyzing actual customers transactions from your customer database, you know this article hits on an important trend. The channels you choose to use in your "marketing mix" attract Judy, Jennifer, or Jasmine ... seldom attracting all three. Your creative strategy attracts Judy, Jennifer, or Jasmine ... seldom attracting all three. Your merchandising strategy plays a role as well ... seldom attracting all three.
You get to pick your customers. Once you pick your customers, the channels that work best are pre-defined for you.