Obviously the math is not rigorous that we use to SUPPORT, not PROVE, an adjustment. Further, using a small data base is fraught with potential problems. I understand the rationale of UC in regard to many houses being fairly simple to make a stab at, and the imprecision allows for some huge potential errors, which are only dampened by our judgment. The notion is recent that we need some sort of precision math to make these judgments. And the blame lies in the idea that Zillow is a precision algorithm which can be replicated by appraisers. Fannie Mae is much smitten by the idea and as crappy an idea as it is, appraisers are dealing with this daily. Again, Thaler has won the Economic Prize from the Swedish Bank on the basis of his research that people are basically irrational and therefore, any model assuming that humans only make decisions on the basis of clear self-interests or they know the difference in what is best for them and what appeals to them is wrong.
I was stuck in the waiting room for an hour waiting on my doctor and had to watch Property Brothers or stick chewing gum in my ears...and I was out of chewing gum. I watched as one of the Weasel brothers negotiated with buyer seller to get into a 1400 SF home for $830,000 with a budget to do some remodeling. Of course, no home inspector was needed. So they start in on the wall, then the fireplace - problems, then the electrical, then find mold in the attic, new membrane roof on low pitch house, and finally, the garage turned out to be an add on with insufficient support and literally has to be rebuilt. All those fancy upgrades had to be downsized and I thought...geez, what a good screwing these people got. But they were led like sheep to the slaughter instead of calling their lawyer and suing. Too embarrassed I suppose to admit they were duped by a slick sales pitch.
so have not read past your response yet.