Besides the frequency and timeliness of survey data, other data
quality issues arise in measuring household living standards. The
surveys ask detailed questions on sources of income and how it
was spent, which must be carefully recorded by trained personnel.
Income is generally more difficult to measure accurately, and consumption
comes closer to the notion of living standards. And income
can vary over time even if living standards do not. But consumption
data are not always available: the latest estimates reported here
use consumption for about two-thirds of countries.