ABAC Survey

There's some interesting ABAC (Assumption Univ) poll stats available at the asiancorrespondent.com/bangkok-pundit-blog (add the www. to the front). The poll focuses on who's supporting who in the various political fronts. But what caught my attention was the stats on income levels.
Of 2250 people surveyed in 12 provinces:
By Monthly Income:

Income under 5,000 Baht, 37.3%
Income below 15,000 Baht a month, 82.3%
Income after 15,000 Baht a month 17.3%

When I see numbers like these, it makes me wonder who's buying all the houses going up in places like Udon. Take a husband and wife who are making the high end of the middle bracket (15k each), but are paying off a vehicle, maybe a motorcycle, a couple of mobile phones, groceries/utilities, lottery tickets, maybe a kid or two, etc, that'd leave precious little for a 10k/month house payment.
I know stats are just that........and maybe living outside the city in a small, poor village doesn't help, but it does make me wonder!!
There's obviously money burning holes in peoples' pockets in Udon, but hearing what people make per month (even at the college grad level) and seeing stats like the ones in the poll always leaves me wondering where the money is coming from.

12 provinces ... which provinces I wonder?

I have no proof, but I'm convinced Thais understate their earnings, their savings, their net worth.
While "appearing" rich is the stereotype we often ascribe to them, "appearing" poor has enormous advantages.
We love to characterize them as recklessly irresponsible with money, but I'm not convinced it applies to all, or even most.
Especially the modest Thai Chinese. And the shrewd Vietnamese.

Also, land is wealth but will not be indicated by a poll on salaries.