Great stuff David. Interestingly enough, in your example the raw $/sq.ft. average is $155/sq.ft. Your conclusion of $38/sq.ft. adjustment factor is 25% of the raw factor. Ratterman threw out 30-40% as examples, but certainly this supports his general idea that the raw $/sq.ft. factor must be significantly discounted...
Actually, all I told you was my figures - the actual spreasheet shown in my post was the one that copied over with my qoute of Meta's original post. That $155 avg was his example, not mine.
My GLA adjustment actually worked out closer to being 40% of my comps' average sales price psf.
Just wanted to squash any confusion before it got going too far. And I've never read the book in question (though I want to now) but I thought it was pretty much common knowledge that the GLA adjustment figure was always discounted from the raw psf figures presented by the comps. At the very least, we need to get the land/lot out of the raw figure before going any further with it. I'll leave the "beds and baths are in the GLA and do not get adjusted twice" argument for those that are more passionate about it than I.
Honestly, the spreadsheet Meta produced was the idea, I just wanted to show anyone wanting to use it how to set it up for more than the 4 comps shown *without* skewing the MAX-MIN analysis. See, if you only have 3 comps, and have slots in the spreadsheet for 4+ then by default all the non-used comps will have zeros at each adjustment level since ultimately X/Y/Z x 0 is 0. Well, a zero (as a literal) would become the MIN across every column and thereby hose all the math - the answers would always be the same as MAX since the MIN would be mistaken as 0 across the blank comps and MAX-0=MAX. So I had to come up with a way to test for zero, and IF zero, insert a blank in lieu of 0. Blank cells are not interpreted as an integer or number in Excel, so they're excluded from any math that calls for their cell #, and the actual MAX-MIN splits are once again calculated and shown properly. SO, I set mine up to require 3 comps (duh) and comps 4-6 are optional, that if left blank, will not screw up the math for the 3 comps that were presented. Of course, you can build a sheet that accounts for as many comps as you wish, and as many GLA adjustment figure columns as you wish too. I think ideally for me, I need 7 comp positions (I do occasionally use 6 comps - which would leave room for a "spare") and GLA adjustment columns from $10 to $125. Since I haven't seen figures that low or high in some years, I figure that range would cover 99% of my cases.
But, I like it. A lot. Will serve as a quick double/triple check on my current methods. The shortcut for this Excel file is already on my desktop next to my various MLS systems' Excel/1004MC worksheets.
