The RAND Health Insurance Experiment (RAND HIE) was a comprehensive study of health care cost, utilization and outcome in the United States. It is the only randomized study of health insurance, and the only study which can give definitive evidence as to the causal effects of different health insurance plans. Most health economics studies are observational, and can only give associational evidence. Although the study was conducted in the 1970's and early 1980's, the results are still highly relevant, since RAND HIE is the only study which can make causal statements.
In 1971, a RAND group, led by health economist Joe Newhouse and including statistician Carl Morris, established an insurance company using funding from the then-United States Department of Health, Education, and Welfare. The company insured 5809 people, randomly assigned to insurance plans that either had no cost-sharing, 25, 50 or 95% copayment rates with a maximum annual payment of $1000.
There are various different types of chess problem:
Directmates - white to move first and checkmate black within a specified number of moves against any defence. These are often referred to as "mate in n", where n is the number of moves within which mate must be delivered. In composing and solving competitions, directmates are further broken down into three classes:
Two-movers - white to move and checkmate black in two moves against any defence


The field of music cognition involves the study of many aspects of music including how it is processed by listeners.
