That doesn ' t seem to square with what Zoopla say about their data , unless I ' m missing something ? The Zoopla valuation algorithm analyses property data on all 27 million UK homes on a continuous basis . We get our data from multiple sources including the government , estate agents , surveyors and our users . Our model looks at the relationships between transaction prices and property characteristics type , style , # of bedrooms , etc . and uses these patterns and trends to estimate present values . Because we add new data all the time , the range of homes for which we can provide instant estimates constantly expands , and the accuracy of our estimates constantly improves . Our estimates are computergenerated . Such a computerbased value estimate system is often known as an Automated Valuation Model AVM . We do this by using each distinct method in proportion to its likely accuracy impact for the specific property . Our algorithm considers previous sold prices for the specific property and recent transactions nearby changes in the market values to similar properties of that type in the local area the various characteristics of the property in question and those around it current asking prices for specific properties and others in the local area the size of the property in question relative to those around itthe current values of comparable properties