interesting snippets of article from redfin.com study on real estate websites...
The Accuracy of Real Estate Websites
When home buyers search for homes for sale online, are they seeing all the homes for sale? Do new listings show up in a timely manner? Are all the homes they are seeing actually still for sale?
To answer these important questions, we analyzed a sample of 6,401 home listings in 33 zip codes from 11 metro areas. The listings analyzed were from three local brokerage sites and two highly trafficked national real estate portals.
The results of this analysis are that the local brokerage sites are considerably more complete, more accurate, and timelier than the national portals.
In each U.S. city or area, all real estate brokerages contribute and share listing data. Only real estate brokers can be members of a local MLS. In contrast, national portals, such as Zillow and Trulia, mostly rely on individual agents and real estate brokerages to re-post their listings on the portal websites, or the portals aggregate data from syndicators of real estate information.
Brokerage Sites Show 100% of the Agent-Listed Homes for Sale
Each of the local real estate brokerage websites analyzed contained 100% of the homes listed for sale in the MLS. Portal sites contained just 79% to 81% of these listings – a fifth of the homes for sale did not appear on portal sites.
The results varied by market, with one or both of the portal sites showing at least 85% of the listings in five markets: Boston (Trulia at 91%), Denver (Zillow at 86%), Philadelphia (Trulia at 93%, Zillow at 86%), San Diego (Trulia at 94%, Zillow at 88%), and Washington DC (Trulia at 86%).
Trulia was missing the most listings in Seattle, where only 63% of the homes for sale appeared on the site. Zillow was missing the most listings in Phoenix, where only 65% of the homes for sale appeared on the site.
Brokerage Sites Show Newly-Listed Homes 7 to 9 Days Faster
Local brokerage sites get home listings from direct feeds provided by the local MLS. In most cases these feeds are updated every 15 to 30 minutes, which allows homes to appear on local brokerage sites as soon as they are listed by an agent. Portal sites obtain their listings from a variety of sources: individual brokerage feeds, third-party listing aggregators, and direct entry by agents. Occasionally portal sites gain access to MLS data, but even when this happens, that access is only partial. The median delay between when a home was listed on the MLS and when it appeared on the portal sites was nine days for Trulia and seven days for Zillow
Brokerage Sites Correctly Remove Homes No Longer for Sale
Since local brokerages update the data on their sites with new information from the MLS as often as every 15 minutes, when a home buyer searches a local brokerage site, there are little to no results that are outdated and no longer for sale. On portal sites, over a third of the results are not really for sale.
Conclusion
MLS-powered local brokerage sites enjoy three major advantages over portal sites:
Brokerage sites show 100% of the agent-listed homes for sale, compared to only 80% on portal sites.
Brokerage sites show new homes for sale seven to nine days earlier than portal sites.
36% of home listings that appear as active on portal sites are no longer for sale.