CHICAGO — Diane Pyshos collects houses.

At the moment, she and her husband, Bill McCollom, have three. They and their son, Thomas, manage to live in all of them, though daily life can be complicated by errant clothing or grocery miscalculations.

"One house has five mustards and the other houses don't have any," she joked. "You forget which house you're supposed to go to."

Not that she's complaining. The couple loves their self-described schizophrenic existence, which revolves around two homes in Michigan (a mere five miles from each other) and one in the Bucktown neighborhood in Chicago. They're thinking about a fourth in Arizona.

They may be on to something. Thanks to a confluence of demographic and economic factors, owning two homes is verging on the commonplace, according to gatherers of real estate data. And now, some numbers crunchers are starting to scrutinize the ranks of owners of three or more homes.

"We call them 'supersplitters,' " said Bill Jacobs, a demographic analyst in Seattle.

Jacobs' firm studied second-home ownership for WCI Communities. The real estate development company in Bonita Springs, Fla., coined the term "splitters" to differentiate an emerging profile of second-home owners from the more traditional snowbirds, who tend to divide their time seasonally.

Splitters, on the other hand, are likely to bounce between homes, relatively speaking. And supersplitters, with three or more homes, elevate that practice into an art form.

Their numbers are nearly impossible to peg. Public property records and lenders' data don't tally how many properties a buyer owns or even how the homes are used. Some third properties are strictly investments, others are for personal use and still others are a blend of both.

In addition, a revival of interest in time-shares and the creation of so-called fractional ownership of vacation properties have put the term "our third place" on many more peoples' lips.

Clearly, these changes have the potential to move multiple-home ownership beyond the confines of the super-rich — who long have trod the Newport, R.I.-to-Palm Beach, Fla.-to-Palm Springs, Calif. circuit — and into the ranks of the "economically comfortable."

They're out there. "Income is tilting toward the top end of the scale," said Peter Francese, a demographer in Exeter, N.H., who said that if third-home ownership isn't entirely mainstream, it's getting closer.

"One-fifth of all households take home 50 percent of all the money in this country," he said. "So, multiple homeowners might have a ski condo in the winter, a summer place on a lake and a regular house they live in the rest of the time."

Market researcher Brooke Warrick said the notion of "escape" is one of the principal motivators for second-home purchases.

Warrick, whose California firm, American Lives, studies consumer behavior for the real estate industry, said he's skeptical of the growth potential of third-home ownership.

"I think there's going to be a backlash, in terms of second and third homes," he said. "People are going to understand that owning these things is a lot of work."