Tim Cook’s Prozac: The Apple Store in three charts by Philip Elmer-DeWitt @FortuneMagazine February 13, 2013, 1:26 PM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons FORTUNE — “I don’t have very many bad days,” Apple AAPL CEO Tim Cook told the audience at Goldman Sachs’ technology conference Tuesday. “But if I ever feel that I’m dropping down from an excited level, I go and visit a store. It’s like a Prozac.” Cook’s point was that Apple’s retail outlets are not like ordinary stores. “I’m not even sure ‘store’ is the right word anymore,” he said. “They’ve taken on a role much broader than that. They are the face of Apple for almost all of our customers.” As if to illustrate that point, two analysts — Asymco‘s Horace Dediu and Needham‘s Charlie Wolf — issued chart-heavy reports on Apple’s retail efforts Wednesday. The news, as Wolf points out, is mixed. Traffic is up (as Dediu’s chart above shows), but same-store sales are down (see Wolf’s chart below). Wolf’s chart shows three periods of rapid same-store sales growth, which he attributes to the waves of foot traffic drawn first by the iPod, then by the iPhone 3G and finally by the iPad. He attributes the failure of same-store sales to keep pace with Apple’s revenue growth to the rapid expansion of the company’s iPhone and iPad distribution networks, which gave people who don’t live near an Apple Store other places to shop. Still, when measured by sales per square foot, Apple Stores are — as Cook suggested — not your typical retail outlet. Dediu’s chart below is drawn from 2012 RetailSails data. For more, see Asymco’s Tim Cook’s comments on Apple Stores, illustrated and Needham’s Wolf Bytes 34.42.