So the urban monetary poverty line should be higher than the rural poverty line. But it is not always clear that the actual difference between urban and rural poverty lines found in practice properly reflects the difference in the cost of living. Sometimes the difference has been so large as to imply that the incidence of poverty is greater in urban than in rural areas, even though the reverse is found when adjustments are made only for differences in the cost of living. As with international comparisons, when the real value of the poverty line varies, it is not clear how meaningful such urban-rural comparisons are. The problems of making poverty comparisons do not end there.
Further issues arise in measuring household living standards.
The choice between income and consumption as a welfare indicator is one issue. Incomes are generally more difficult to measure accurately, and consumption accords better with the idea of the standard of living than does income, which can vary over time even if the standard of living does not. But consumption data are not always available, and when they are not there is little choice but to use income. There are still other problems. Household survey questionnaires can differ widely, for example, in the number of distinct categories of consumer goods they identify.