Closing the Rich-Poor Gap?

Daily News and Analysis (DNA) India has this report:

Thimphu: In a finding that is bound to bring smiles to Bhutan's advocates of
gross national happiness, a recent study has shown that the gap between the
country's rich and the poor is closing with the number of people living below
the poverty line dropping significantly.

Now, how true that would be is left to be seen. It further states:

The number of Bhutanese living below the national poverty line has dropped from
31.7 percent in 2004 to 23.2 percent of the total population, according to the
2007 Bhutan Living Standard Survey (BLSS) carried out by the National
Statistical Bureau.

Are most of the Bhutanese folks really poor? How do we measure poverty?

The national poverty line has been established at a minimum monthly earning of
Nu 1,096 per person, with estimated food requirement at Nu 688 and non-food
requirement of Nu 408. Previously, the poverty line put the minimum monthly
earning at Nu 740 a month.

Are the statistical measurement reliable? How many people did they survey? Did they really go to each household for their findings?

The report also says that poverty in Bhutan was still a rural phenomenon with higher rates found in Zhemgang, Samtse, Mongar, Lhuentse and Samdrup Jongkhar.

30.9 percent of rural Bhutan fall below the poverty line compared to 1.7 in the urban areas. "The gap between the rich and the poor is also closing, though not significantly," an official was quoted as saying.

The survey, which focused solely on poverty analysis, puts the number of people below the poverty line at 146,100 out of an extrapolated population figure of 630,000.

The NSB estimated the population in 2007 at 658,888, a projection based on the 2005s National Housing and Population census, which put the resident population at 634,982.