Rule #1 never claim your using paired sales if there not in your grid.
Absolutely. But you need to show some charts, or graphs, to show that you at least tried to not to use the cheat sheet. I have several charts, GLA, regression & sensitivity. The reader sees a simple graph or chart and they think you at least tried to find the adjustment.
In the comment below it also says why there may not be a math way to prove it. My appraisal is actually my work file, cause 3 years from now i won't remember how i did it.
I will say that in my big urban life, mostly GLA and condition adjustment only.
This is a good reference to, in my report:
The Appraising Residential Properties, 4th Edition, Appraisal Institute, "Other Quantitative Adjustment Techniques”, Page 344 further states: “…In instances where paired sales analysis is not conclusive, the appraiser may apply judgment to resolve the problem." The adjustments resulting from the appraiser's judgment is based on a study and understanding of historic or past buyer preferences. It further suggests that cost and depreciated cost data may be used with the appraiser arriving at the value contribution (not cost new) of certain features. The process of supporting the contribution of individual variables (features) is limited and often difficult to quantify, with adjustment deemed to be qualitatively supported unless otherwise addressed. All methods of supporting adjustments are usually limited by inherent uncertainties within the applications themselves.
Adjustments, in this report, are based on a combination of Paired Analysis with Sensitivity and/or Trend Analysis & on a study and understanding of historic or past buyer preferences. Support for adjustments may be based on multiple applications and rarely do two methods return identical results with a high degree of accuracy. While not always 'strongly' independently supported, collectively the adjustments serve to narrow the adjusted value range of comparables in support of the market value opinion, the subject's 'most probable selling price' commensurate with the definition of Market Value set forth herein.