The most we can hope for is a useful research tool that is easily understood and widely accepted. Some poverty lines are better than others at measuring changes in poverty over time. That is a very desirable feature, because it allows researchers to see the impact of changes in economic conditions or changes in government policy. Statistics Canada's low income cut-offs are very good in reflecting the ups and downs of the economic cycle. However, poverty lines based on average or median income tend to change very little from year to year and are much less useful in measuring poverty over time.
Some poverty lines are better than others because they focus on disposable income or cash on hand.
The low income cut-offs are based on income after government transfer payments such as welfare, unemployment insurance or the Canada Child Tax Benefit but before income taxes. Most market basket poverty lines are after-tax measures that reflect the cost of sales taxes as well as income taxes. That is because people actually purchase the items in the market basket, and they have to pay any federal, provincial or territorial sales taxes on taxable items when they make their purchases. Some poverty lines are better than others because they are easily understood and therefore easily accepted. One of the problems that has dogged the low income cut-offs is the fact that the methodology used to derive the lines is not easily explained.