Until recently, researchers had not tried to answer that question.

A new study* by three academic researchers has tried to find out.

Similar results occurred when the researchers tried to test themselves.

Researchers are certainly trying to improve the situation, in part because there is money to be made.

The researchers try to control for some of these factors, but they can't rule them out.

In phase I, researchers try to find out if the drug is safe for people to take.

Researchers next tried to determine the purpose of the structure.

But when researchers tried the procedure in people, it usually failed.

The researchers are still trying to determine why men without wives face a greater risk of early death.

But when researchers tried to prove the theory, they kept coming up empty.