Automated Valuation Models are usually used by lenders for property estimates. It is a fancy term for determining value by platforms such as Zillow. Typically the value is by creating a radius search of county sold data and figuring out an average price per square foot.
This type of valuation works ok in homogeneous tract neighborhoods, but not so well in areas with a lot of variation. Also since the computer is strictly averaging numbers,and it does not adjust for condition, view, or other things. It is a decent starting place as far as determining the average area value, but should not be considered on par with an appraisal or Realtors comparative market analysis, or even a BPO.