Standard courses in economics talk about the law of demand and supply, where prices are determined to equate the two. Joseph Stiglitz: The 99 Percent Wakes Up Joseph E. Stiglitz May 1, 2012. Those ships he speaks of equate to jobs at shipyards, the planes to jobs at Boeing/Lockeed/etc.
An exercise stress test is designed to find out if one or more of the coronary arteries feeding the heart contain fatty deposits (plaques) that block a blood vessel 70% or more. Additional testing is often required to confirm the test result. Test result.
Cardiac exercise stress testing: What it can and cannot tell you. Harvard Men's Health Watch. This procedure helps determine your risk of heart disease, but follow-up testing is often required to be certain.