We examine why managed care plans are less expensive than traditional indemnity insurance plans. Our database consists of the insurance experiences of over 200,000 state and local employees in Massachusetts and their families, who are insured in a single pool. Within this group, average HMO...

This study assesses the factors influencing the movement of people across health plans. We distinguish three types of cost-related transitions: adverse selection, the movement of the less healthy to more generous plans; adverse retention, the tendency for people to stay where they are when they...

Individual choice over health insurance policies may result in risk-based sorting across plans. Such adverse selection induces three types of losses: efficiency losses from individuals being allocated to the wrong plans; risk sharing losses since premium variability is increased; and losses from...

We examine why managed care plans are less expensive than traditional indemnity insurance plans. Our database consists of the insurance experiences of over 200,000 state and local employees in Massachusetts and their families, who are insured in a single pool. Within this group, average HMO...