Regression is an economic principle of value that states that, between dissimilar properties, the value of the better property is adversely affected by the lesser quality property.
Regression is non-conformity that decreases relative value in a neighborhood. The value of superior houses tend to be pulled down because of the presence of inferior houses.
Regression is the same as progression except in reverse.
A house that is larger than others in the subdivision will usually sell for less than a similar house in a nearby subdivision where the houses are similar in size.
Example: A 3,000 square foot contemporary house will be out of place in a subdivision consisting of 1,500 square foot traditional ranch houses. It will sell for less than a similar house in a nearby conforming neighborhood. This is an example of nonconformity causing regression.