Linda Raymond of Chantilly has one goal when she goes to the supermarket: to get out as fast as she can.

"I am the world's fastest shopper," says Raymond, "because I hate grocery shopping. I hate the money you have to spend. I hate the long lines and the stupid cards you have to use everywhere to get a discount," she adds, as she loads her car with groceries outside a Giant supermarket in Herndon.

The mother of an "always hungry" teenage son, Raymond shops three or four times a week. She also works full time and wishes that supermarkets would do more to make shopping fast and convenient. Her suggestions: more express lines and more quick pickup items near the entrance. "Why do I have to go all the way to the back of the store if all I need is milk?" she asks.

Raymond isn't the only one who'd like to see some changes at the grocery store.

Three University of Pennsylvania marketing experts say the supermarket industry has been slow to respond to consumer needs, in part because grocery chains have some outmoded ideas of how people really shop.

Peter S. Fader, Eric T. Bradlow and Jeffrey S. Larson, all of the Wharton School, analyzed data from special tracking devices attached to shopping carts at one West Coast supermarket. The data from 2004 showed, they say, that shoppers move through a store in a very different way than many retailers realize.

Among their findings: Shoppers like to go in a counterclockwise direction; they don't weave up and down every aisle, in fact they rarely go all the way down any aisle; and to speed things up, they stick to the perimeter and avoid huge chunks of the store.

Fader, a professor of marketing, believes the grocery industry has spent too much time focusing on such things as loyalty programs (discount cards, for example) and not enough time on store layouts that meet shoppers' needs.

But a spokesman for the grocery industry says supermarkets do understand consumer buying behavior. "We know consumers are time-starved," says Stephen Sibert, vice president for industry development and membership with the Grocery Manufacturers of America. Sibert says supermarkets are trying new ways to help shoppers, including cooking demonstrations, grouping together products for special events such as graduation parties, and improving store layouts.

As it turns out, a convenient layout that makes it easy to shop is important to 93 percent of customers, according to the 2005 "U.S. Grocery Shopper Trends" report, released last month by the Food Marketing Institute, the industry's trade association.

Traditionally a phone survey of 500 shoppers, this year's report used the Internet to survey 2,001 shoppers. Conducted by Harris Poll Online, the survey showed that while shoppers want bargains, they -- like Raymond -- increasingly value speed and convenience when they choose a place to buy their food.

Those surveyed said they'd shop at their neighborhood supermarket more often if the stores had faster checkout, a quick-stop area for things such as bread and milk, and a convenient spot where shoppers could pick up items for that night's dinner, such as pasta, salad and dessert.

Quick trips, in particular, are a growing trend among shoppers, who might not think about what to make for dinner until they're driving home at the end of the day. In fact, the traditional once-a-week trip to the market to stock up on groceries is fast becoming a relic.

In a new study of 2,400 shoppers by the food and consumer products giant Unilever, the classic stock-up trip accounted for only 10 percent of all grocery store visits. Nearly two-thirds (62 percent) were quick trips -- to grab a few emergency items or buy food for the next day or two.

This is significant for supermarkets that don't want to lose customers to convenience stores, where it's often easier to buy a few items and check out quickly.

Karen Brown, senior vice president of FMI, says grocery retailers realize that shoppers "don't want to spend a large amount of time in the grocery store." She says a lot of experimentation has taken place in store layout over the past six years "as retailers try to figure out how to make the shopping experience more convenient."

Retailers "are trying to mix it up a bit," she says.

Fader thinks they could do more. He believes supermarkets should follow the lead of online companies, which track every mouse click a shopper makes and use the information to design more user-friendly Web sites.

Online merchants "can see what people look at, what they choose and what they delete. Supermarkets have just been interested in what people buy. They need to look at the whole process," Fader says.

He acknowledges that the Wharton study is based on only one supermarket and cannot be applied to all grocery stores, but he says it represents the type of research the industry should do.

The Wharton group used data supplied by Sorensen Associates Inc., an Oregon-based retail research firm that provided the shopping cart tracking devices.

President Herb Sorensen says his company has been using the devices for four years, helping clients track how long their customers spend shopping, where they go in the store and how many items they buy.

For example, a large East Coast supermarket recently hired Sorenson's company to determine what proportion of its customers came to the store for the type of quick trips noted in the Unilever study.

"They were shocked to find out that two-thirds of their customers came in for just a few items. It made them realize that anything to speed the checkout process was important," he said.

Sorensen, who has 35 years' experience in retail research, says supermarkets need to change their approach.

"Supermarkets have been passive, acting like mini-warehouses, stocking items here and there and expecting the shoppers to find what they want.

"They need to be more active," he says. "They need to know what their shoppers might buy, offer it to them early [in their shopping trip] and speed them through the checkout."