The Zip Code Effect found that wealthier neighborhoods field stronger teams. But a nagging question sits underneath it: do wealthy areas actually produce better soccer, or do they just build bigger schools, and it's the size doing the work? Bigger schools have more bodies to find eleven starters from. So which is it, the money or the size?
Take every public program with both a Census wealth score and an enrollment count, and correlate each against ELO. Neighborhood wealth is a real signal, as the earlier report showed. But raw head count is a stronger one, especially on the boys' side:
Both matter, and they are related. But before crowning size, we have to rule out the obvious trap: what if bigger schools are simply in wealthier areas, and enrollment is just wealth wearing a different hat?
Partly. Across these public programs, enrollment and neighborhood wealth correlate at 0.41, so richer areas do tend to run somewhat larger schools. That overlap is real and worth naming. But it is far from total, which lets us do the honest test: strip out everything enrollment shares with wealth, and see whether the leftover size still predicts winning.
It does. After controlling for neighborhood wealth, the independent effect of size on ELO is still 0.37 for boys and 0.27 for girls. Size is not a wealth proxy. Two schools in equally well-off neighborhoods, the bigger one is meaningfully more likely to be the stronger program. More students is more raw material, and it shows.
The plainest view: sort public programs into four groups by size and read off the average rating and the average neighborhood wealth of each.
The smallest quarter of schools sits near the bottom of the rating scale; the largest quarter sits near the top, a gap of well over two hundred ELO. And notice the wealth column climbs too, but not fast enough to explain the whole rise, which is exactly what the controlled number already told us.
It's both, but size does more of the lifting than the zip code series alone suggested. Enrollment out-predicts neighborhood wealth for boys and matches it for girls, and its effect survives once you control for wealth. Bigger schools win because a larger student body is a larger talent pool, not merely because larger schools happen to sit in richer places.
This is also why the site rates boys and girls in separate pools and why classification exists at all: TSSAA sorts schools by size precisely because size is the single most legible driver of competitive strength. The wealth effect is real and worth studying. But when you ask a rating where a program will land before it plays a game, "how many kids go there" is the better first question than "how rich is the neighborhood."