Why does my home's Zillow estimate decline while my neighbors' estimates rise?

Thanks, Bradley.  Since you asked, I'll tell you a little about the homes in the area.  Small to mid sized homes -- very few sales or for sale.  Homes that come up for sale sell very quickly if priced within 15 to 20% of Zillow estimate. Houses and lawns are neat, well kept, and in good condition.  My house is the only house in the immediate area of adjoining neighbors that has gone down in value steadily (on zillow) over the past six months.  The neighbor I mentioned earlier has a 1 bed, 1 bath with basement and detatched one car garage.  My home is a 2 bed, 1 bath with no basement and attached one car garage.  Both are very neat and attractived houses inside and out and similar in appearance on identical lot sizes.  My home is appraised for taxes at $69,500 (zillow $71,000 or $1,500 difference), and the next door neighbor's tax appraisal is $62,500 (zillow $76,000 or $13500 difference). This, of course, is public information, and I have a hard time understanding what other criteria zillow is using to cause such a discrepancy and such broad value swings in opposite directions for homes next door to each other.  Again, Thanks for your response to my question.  Let me know if you have any other thoughts.  Jim

How nearly identical? Zillow is only an estimating program that can't take anything more than basic public information into effect. It's influenced by recent sales. Sometimes bigger homes or homes with an extra bed/bath/garage/etc either aren't selling as fast or are more inundated with distressed sales than smaller/lesser ones, so the trend overall for better houses might actually be going down while smaller might be going up. Keep in mind, Zillow is just a calculating estimating machine. They try their best but it's not meant to be a reliable indicator of full market value, especially used to compare one house against another.