Appraisers use the Sales Comparison Approach (SCA). Realtors use a Comparative Market Analysis. While similar, the appraiser will detail their findings in an appraiser report. A good Realtor is usually not far off the appraisers' report. Sometimes though an appraisal will come in higher or lower than the listing price.

What factors can you think of that may cause an appraisal to come in higher? Lower? Why?