Though customers who shop multiple channels of the same retailer buy more than those who shop a single channel, they can be more expensive to maintain, according to Jupiter Research, writes InternetRetailer. Some 28 percent of U.S. online buyers make purchases at the same store across multiple channels, Jupiter found, and they buy on average 14 percent more per year. But they're also more likely to use a retailer's cost centers.

Compared with single-channel buyers, they're 28 percent more likely to contact customer service reps after a purchase and 26 percent more likely to say store coupons influence their decision to keep buying from the same retailer.

Jupiter' recommends that retailers measure customers on gross-margin and lifetime value to accurately determine their true value and accordingly allocate spending.