For statistical purposes (e.g., counting the poor population), the Census Bureau uses a set of annual income levels — the poverty thresholds — slightly different than the federal poverty guidelines. As with the poverty guidelines, they represent a federal government estimate of the point below which a household of a given size has cash income insufficient to meet minimal food and other basic needs. They were developed in the 1960s, based largely on estimates of the minimal cost of food needs, to measure changes in the poor population. The thresholds form the basis for calculating the poverty guidelines, and, like them differ by household size and are adjusted annually for overall inflation. But, they do not include different levels for Alaska and Hawaii, and include separate levels for small elderly households.