It takes more than anonymous algorithm to evaluate a home's value. There is the old location times 3, quality of construction, curb appeal. When fluctuations of my home's, quite unrealistically, value drops by almost 20%, according to Zillow, in basically a flat to growing market, over a couple of months, something is terribly wrong. Especially when Zillow changes their valuation graph to agree with their new estimate, not showing the higher evaluation as part of their presentation which appeared on earlier graphs. Original estimate was closer to reality in the first place. Almost all of the realtors whom I speak with think Zillow leaves a great deal to be desired regarding information when purchasing a house in S. W. Florida... Do your own due diligence and avoid being misinformed and possibly missing out.