How much more do home buyers pay for better schools? WASHINGTON - It's a key question for many home buyers who have or plan to have young children: We want a house in an area with good schools, but what price premium - if any - will we have to pay? Academic research generally has found that, all other factors being held equal, you pay somewhat more for houses in highly rated school districts compared with homes in neighborhoods where the schools have lower ratings and test results. Now a national realty brokerage, Redfin, has come out with a study that purports to put hard numbers on the pricing differential. Using a huge database of about 407,000 home sales and nearly 11,000 elementary school districts in 57 metropolitan markets, the study concluded that, on average, buyers pay $50 more per square foot for homes in top-rated school districts compared with homes served by average-rated schools. The study's data came from multiple listing services plus school characteristics and test scores provided by research firms GreatSchools and Onboard Informatics. The net result, according to Redfin, is that the price differentials for similar homes - same square footage, number of bedrooms and bathrooms - that are located near each other but served by different school districts can range from tens of thousands to hundreds of thousands of dollars. In some expensive areas, such as coastal California, "homes in the highest ranking school zones" come with cost differentials ranging from $300,000 to nearly $500,000. Even when similar homes are separated by just a school district dividing line from each other - half a mile to three-quarters of a mile apart - the price gaps can be significant. To illustrate the point, the study focused on five pairs of recent home sales. One case in Alexandria, Va., involved what Redfin termed "nearly identical" homes - both with four bedrooms, three baths and 3,000 square feet of living space - located three-quarters of a mile apart. For one house, the local school ratings were high. For the other, lower. The price premium: $130,000, or 16%. The study offered parallel examples in San Diego, Seattle, Gilbert, Ariz., and Beaverton, Ore. Researchers found large pricing differences between home sales in highly rated school districts compared with average-ranked districts in major metropolitan areas from coast to coast, including Los Angeles; Boston; Miami; Washington, D.C.; Charlotte, N.C.; Chicago, Seattle; San Diego; San Antonio; and Las Vegas, among others. The study defined top-rated schools as those with test scores in the 90th percentile and above in their respective states and average schools as those in the 40th to 60th percentiles. But hold on. Could these apparently large pricing differences be attributable solely to school quality? Are test scores from elementary schools really so powerful that they can add such hefty premiums onto the prices of "identical" houses that are simply on different sides of a district school line? Take another look at the Redfin study. Unlike academic studies that employ sophisticated statistical techniques to separate out multiple other variables that may be influencing pricing disparities, Redfin did no regression analyses on its data. Tommy Unger, the principal researcher for the study, conceded to me in an interview that "we wanted to tell the high-level story" for the home buyer, and therefore did not analyze the data with the sort of statistical rigor that would be necessary for an academic paper designed to prove a point scientifically - in this case, how much extra buyers pay for top schools. Also, although the study said the houses it used for comparison were "identical," there was no attempt at creating true "comparables" as in an appraisal report detailing interior condition, improvements, neighborhood facilities and amenities, views and other locational pluses and minuses - all of which can affect pricing. The homes highlighted in the study were similar in numbers of bedrooms, baths and interior square footage. Potentially that leaves out a lot. For example, in the pair of Virginia houses selected to show a $130,000 price disparity across school lines, local real estate agents said there were important differences that the Redfin analysis missed: a community pool open to all residents in the higher-priced neighborhood, a strong sense of community involvement, and "walkability" designed into the neighborhood's physical layout - all of which increase value. "All the boxes are checked" to make that neighborhood more attractive and in demand, said Sue Goodhart, a broker with McEnearney Associates Inc., a firm that specializes in the area. It's just not all about the schools. Distributed by Washington Post Writers Group.