SN ASKS: CHARTING SHOPPING TRIPS

Julie Gallagher

PHILADELPHIA -- Though scores of studies have attempted to zero in on the purchasing habits of consumers, few have been able to examine the actual paths that shoppers take through a store. Thanks to radio frequency identification technology, Wharton marketing professor Peter Fader and his colleagues at the University of Pennsylvania here have been able to focus exclusively on shoppers' in-store routes. Their study, "An Exploratory Look at Supermarket Shopping Paths," was based on RFID-tracking data on 60,000 shoppers collected by Sorenson Associates, Portland, Ore. Sorenson used "active" RFID tags attached to the bottom of shopping carts. Unlike more common "passive" tags, these tags emit a signal every four seconds, which in the study was picked up by antennas strategically placed around the perimeter of participating stores. "The antenna hears the tag and [the cart's] distance is computed," said Herb Sorenson, president and chief executive officer. A clustering algorithm identified 14 distinct grocery store travel paths that encompassed short, medium and long shopping trips.

SN: Why was RFID used to facilitate this study?

FADER: In the old days, research like this was done by following the shopper around the store with a clipboard and marking down the time spent in the aisles and the products they picked up. This method was inefficient. RFID lets us automate the process. Reviewing the information produced from this research was like putting on glasses for the first time, because things became much sharper. Now there is an incredible amount of data, and the richness of it is one of its most distinguishing features.

SN: Did the RFID technology allow you to know when a shopper stopped to select an item?

FADER: As part of this study we tracked the cart and not the person. So if the shopper left their cart and wandered over to select an item, we have no way of knowing that. We can match a shopper with their purchases, but we don't know how long the person spent selecting items. Gaining that sort of insight is a lot harder because it would mean attaching RFID tags to people. Although purchase information was available, we ignored it for this particular study. What we were really interested in was studying the ways shopping carts wander around the store.

SN: What was the most surprising result of this study?

FADER: It sounds boring, but it's the variability of the findings. Few shopping trips go up and down a lot of aisles. I would figure that most shoppers would go down most aisles, but it's an incredibly small proportion. The stereotypical trip doesn't exist and neither does another type of trip in its place. It seems like you put a bunch of ants down and they're running around like crazy. There are so many types of shopping trips that it's hard to design a merchandising strategy around a single notion of the way people shop.

SN: Based on the study's findings, how should retailers change their store design and product placement to improve sales?

FADER: A couple of ideas jump right out. One of the points raised by the study was the prevalence of counterclockwise shopping behavior. There is so much evidence that shows us that in the U.S. and other right-side-driving countries, shoppers want to shop counterclockwise. A store's entrance also influences this behavior. If the entrance is on the right, shoppers tend to shop counterclockwise. If it is on the left, two things tend to happen. Shoppers will cut across the store and shop backwards, or they will shop clockwise. But clockwise trips are much shorter, and shoppers won't spend as much. If the retailer is smart, over time they might realize that stores with entrances on the right tend to do better. It's important to recognize and adapt to customer patterns rather than trying to influence them. Stores can't push customers around in the way they want them to shop because customers will do what they want to do, and their patterns are highly unpredictable. It's very important for retailers to constantly experiment by doing things like moving merchandise. Maybe that means having different stores with different layouts rather than saying, "Here is a store that works, so let's use its layout over and over again." Most retailers don't want to [experiment.]

SN: What does the study suggest about impulse purchases?

FADER: One of the interesting findings of this study is that shoppers speed up as they go along. Their trip starts slowly and gets faster and faster so as they near checkout they are zipping along. So the impulse items won't get picked up late in the trip. Contemplative moods tend to be experienced earlier in the trip.