How do appraisers select comparables (comps) when appraising a home?

Appraisers select comparable sales from recently sold homes that are similar to the subject property and located close to it. Guidance from the National Credit Union Administration (NCUA) describes comps as generally located within a mile of the property, in similar condition, and close in age, square footage, and number of rooms. The appraiser then adjusts for differences between the comps and the subject property when reconciling a final value.