SANTA ROSA, Calif. — Store manager Jenine Bryant scanned the entrance of the Best Buy, sizing up each customer passing through. A blond woman in a fashionable white shirt and flower-patterned pants wandered in unsteadily, fumbling in her purse for a scrap of paper.

She looked at it, then looked up at the signs denoting how the store is laid out, and then she looked down and up again. Bryant recognized her immediately and rushed over.

The woman was a "Jill" — code name for a soccer mom type who is the main shopper for the family but usually avoids electronics stores. Well-educated and usually confident, she is intimidated by the products at Best Buy and the clerks who spout words like gigabytes and megapixels.

Best Buy Co. is trying to change that by giving her the rock-star treatment at selected stores, sending sales associates with pink umbrellas to escort the Jills to and from their cars on rainy days and hoisting giant posters in the stores that pay homage to the Jills and their children, who are shown playing with the latest high-tech gadgets.

Big chain stores used to be among the most egalitarian of places. They were aimed at the average person, the generic "shopper," without conscious regard to background, race, religion or sex. That is changing as computer databases have allowed corporations to gather an unparalleled amount of data about their customers. Many retailers are analyzing the data to figure out which customers are the most profitable — and the least — and to adjust their policies accordingly.

Express clothing stores no longer accept returns from those whom the company deems to be serial returners. Filene's Basement has even gone so far as to ban a few customers from its stores because of excessive returns and complaints.

Best Buy Chief Executive Bradbury Anderson, inspired by Columbia University professor Larry Selden's book, "Angel Customers and Demon Customers," is on a mission to reinvent how the company thinks about its customers. Best Buy has pared some less desirable shoppers from its mailing lists and tightened up its return policy.

It has also begun to woo a roster of shopper profiles, each given a name: Buzz (the young tech enthusiast), Barry (the wealthy professional), Ray (the family man) and, especially, Jill.

Working with analyses of databases of purchases, local census numbers, surveys of customers, and focus groups, Best Buy last fall started converting its 67 California stores to cater to one or more of those segments of its shopping population. It plans to roll out a similar redesign at its 660 stores nationwide over the next three years. Three Best Buys in the Washington area, for instance, are being transformed into stores for Barrys, featuring leather couches where one might imagine enjoying a drink and a cigar while watching a large-screen TV.

The Santa Rosa Best Buy, Store 120, is Jill's store.

Pink, red and white balloons festoon the entrance. TVs play "The Incredibles." There is an expanded selection of home appliances and displays stocked with Hello Kitty, Barbie and SpongeBob SquarePants electronic equipment. Nooks are set up to look like dorms or recreation rooms where mom and the children can play with high-tech gadgets.

Best Buy has new express checkout lines for Jill. Store managers say anyone can use them — but if you are not escorted by a special service representative, they can be easy to miss. The music over the loudspeakers has been turned down a notch and is usually a selection of Jill's favorites, such as James Taylor and Mariah Carey.

But who exactly is Jill?

"She's very smart and affluent," Best Buy employee Jenn Metzger said.

"Jill is a decision maker. She is the CEO of the household," said Tony Sagastume, general manager for the Santa Rosa Best Buy.