I'll start here:
Avalon at Lexington Hills was going to be 430 units, but was reduced (presumably at the town's behest) to 390, 25% affordable. The assessed value in 2011 is less than was projected when it was proposed in 2004 (little thing happened in between then and now, perhaps you recall it), thus reducing the expected property tax collected from the complex. And they got more schoolkids than they were anticipating. They projected "between 67 and 125 new students to Lexington’s public schools"; they got 166.
What would I have predicted? Nationally, as of 2010, multifamily runs 2.4 people per unit vs. 2.5 in single family. I would have assumed that while some households would have had 2.4 adults and some households would have had a lone adult with 1.4 kids, I couldn't guess which way the fraction would lean. I know metrowest runs heavy to two adult families, and assumed the .4 was all kids. Thus:
390 * .4 = 156.
Unreasonably assuming 100% occupancy -- but I also know that there's a lot of 3 bedrooms in these developments and the Lexington school district is awe-inspiringly good, if your family doesn't suffer from debilitating anxiety in the face of how competitive it is. I would sort of assume that 3 bedrooms in Lexington would attract a disproportionate number of 2 kid families.
I would have come in low, altho not particularly low.
"There was also a failsafe built into the deal brokered between the town and the developer. For every public school student over 111 coming from Avalon, the developer would provide roughly $7,100, the incremental cost of educating that student. Per the agreement, total compensation to the town is limited to $750,000 within 10 years. That cap was reached in the current fiscal year, with the town only able to collect about $331,000 of the $390,500 associated with the 55 additional students coming from Avalon."
That $7100 incremental cost caught my eye -- that sounds low to me based on some research I've done in the past, but never mind that now. That's an amazing deal the town cut with Avalon.
I liked this remark. A lot.
""Something in the intervening seven years changed the normal Lexington response to multi-family housing,” said Connery. “You may be seeing the beginnings of a shift to rental housing in a place like Lexington that has a high-quality school system.”"
Yup. Consistently high gas prices and a massive housing crash. Unemployment around here isn't too bad, especially compared to a lot of the country and, as mentioned above, Lexington school district is excellent.
R. says that when you look at Waltham via satellite view on google, it's densely multifamily, colonizing Lexington. That suggests that the wave outward from the center is currently cresting in Lexington, which goes a long way to explaining Concord being weird on the subject: they know they're next.
ETA: I'm inclined to think that Mehr is full of it, however, I also think that the expected number of kids was ridiculously low. Whether I would have thought that in 2004 is an entirely other question, however, which should make my opinion on this subject very uninteresting.