This topic contains information on selection of comparable sales, including:
selling-guide.fanniemae.com
When choosing comparable sales, the appraiser should examine the market area of the subject property, assess its characteristics, and identify similar comparable sales. Market area is defined as the geographic region, for a subject property, from which most demand comes and in which most of the competition is located. This does not mean comparable sales must be identical to the subject property, but instead should be competitive and appeal to the same market participants that would also consider purchasing the subject property. If the available comparable sales are not similar, the appraiser needs to decide whether an expansion of the market area search is appropriate. If this occurs, the appraiser must provide commentary to explain the rationale for selecting comparable sales outside the subject's market area and make location adjustments if warranted.
Comparable sales from within the same market area (including subdivision or project) as the subject property should be used when possible and must be used in certain instances (see below). Sale activity from within the neighborhood is the best indicator of value as sales prices of comparable properties from the same location should reflect the same positive and negative location characteristics.
Fannie Mae does allow for the use of comparable sales located in competing market areas, as these may simply be the best comparables available and the most appropriate for the appraiser’s analysis. If this situation arises,
the appraiser must not expand the neighborhood boundaries just to encompass the comparables selected. The appraiser must indicate the comparables are from a competing neighborhood and address any differences that exist. The appraiser must also provide an explanation as to why they used the specific comparable sales in the appraisal report and include a discussion of how a competing neighborhood is comparable to the subject's neighborhood.