1. A method of providing comparative cost information for health insurance plans comprising the steps of: incorporating parameters of health plans; assembling recent health care use and cost data for a reference population; acquiring personal and health information from users on themselves and their household members; estimating the distribution of out-of-pocket costs the user and his/her household is likely to face in the coming year in various health plans, based on the experience of comparable households in the reference population; and outputting premium and estimated out-of-pocket expenses.