In lines which are drawn from market baskets of goods and services, someone has to decide what goes in the basket and what does not. That is not nearly as easy as it sounds. The answers to these and a host of other questions determine the overall cost of the market basket. Poverty lines are a research tool for measuring the incomes of groups of people, not a measure of individual need . The primary limitation of both statistical poverty lines and market baskets of goods and services is that they cannot cover all the exceptions to the rule.
Poverty lines work best when they are used to measure the incomes of large groups of people.
They work worst when people try to apply them to individuals. Take the cost of housing, for example. Some people have mortgages and others do not. Some people live in government-subsidized housing. Some people live in well-insulated apartments where the rent includes heating, while others rent houses which are poorly insulated and have to pay sizable heating bills on their own.