How is Zestimate Market Value Change for a specific home calculated over time?Market Value Change charts have been showing dramatic drops in house values the past few weeks. When one looks at the trends for zip code (97341 or 97367), city, county and state, the trends have remained relatively level. How are Market Value Change for a specific home calculated ? December 22 2009 - US0YesReport a ProblemProblemSelect oneOffensive contentIrrelevant contentSpam (pure self-promotion)OtherDetailsYour emailPlease enter a valid email address.Submit CancelContent flaggedWe will review this content. Thanks for helping make the site more useful to everyone. To learn more, read Zillow's Good Neighbor Policy.We're sorry. This service is temporarily unavailable. Please come back later and try again.