SVI does align with Fannie, Freddie and FHA for an allowable number of comparables. It is important to recognize that market data is different from true comparables. Per the Fannie Mae Selling Guide: The appraiser is responsible for determining which comparables are the best and most appropriate for the assignment. Fannie Mae expects the appraiser to account for all factors that affect value when completing the analysis. Comparable sales should have similar physical and legal characteristics when compared to the subject property. These characteristics include, but are not limited to, site, room count, gross living area, style and condition. This does not mean that the comparable must be identical to the subject property, but it should be competitive and appeal to the same market participants that would also consider purchasing the subject property. Comparables that are significantly different from the subject property may be acceptable; however, the appraiser must describe the differences, consider these factors in the market value, and provide an explanation justifying the use of the comparable(s).