This dataset has two files, one for plan-level data ("HMO_premium_dataset_plans") and one for state-level data ("HMO_premium_dataset_states"). The file "HMO_premium_dataset_plans" has one row for each of the 341 plans and six columns in order from left to right: the state, a two-character code that identifies plans within state, the total premium for an individual (dollars), the total premium for a family (dollars), the total enrollment of federal employees as individuals (number of persons), and the total enrollment of federal employees as families (number of families). The file "HMO_premium_dataset_states" has one row for each of the 45 states or other jurisdictions (called "states" for convenience) in the dataset. The four columns, from left to right are: the state (two-letter abbreviation), the state average expenses per admission (dollars; American Medical Association 1991 Annual Survey of Hospitals), population (1990 US Census), and region (from the Marion Merrill Dow Managed Care Digest 1991), using these abbreviations: MA = Middle Atlantic MT = Mountain NC = North Central NE = New England PA = Pacific SA = South Atlantic SC = South Central.