How Redfin Prepares Its Monthly Real Estate Reports

Redfin's real estate market reports draw data from more sources than any other, including the Multiple Listing Services (MLSs) that brokers use to take properties on and off the market in real time; for-sale-by-owner websites used to market properties unrepresented by brokers; government records that officially record any property sale; and government records on city and county borders. Because Redfin as a broker has access to MLS databases, it is able to identify market changes before sales are publicly recorded. Unlike other reports, Redfin also provides county-, city-, neighborhood- and zip code-level detail, disclosing the number of records available in each area.

No report based on tens of thousands of records, all captured by human beings, can eliminate every error, but Redfin has been careful to do so wherever reasonably possible. Reconciling multiple data sources allows Redfin to correct errors in each; sales aren't double-counted, and records for the same property but with conflicting prices and square footages are flagged for further analysis. To aid in interpreting sales volume, Redfin reports changes in number of homes sold in two ways: a simple total month-over-month change, and an average weekday rate that accounts for the varying number of days each month when sales can close. The number of sales and pricing reported in a given month may change the next month to account for any sales recorded in the previous month after we publish our report. The report analyzes houses, condominiums, and townhouses separately.

Redfin does not consider sales that have subdivided, that are the likely result of a sale between family members or to a trustee, or that have likely been improperly recorded. For example, Redfin removes from its analyses records of sales occurring within two weeks of one another, sales in which prices doubled or halved in less than a year, or sales where the price per square foot deviates from the area norm by a factor of four. People on Redfin's data team comb through the reports, examining individual records to understand if outliers are legitimate phenomena or the result of data errors.

Questions about Redfin's reporting methodology can be directed to techsupport@redfin.com.