Everything else held constant, a decrease in marginal tax rates would likely have the effect of ________ the demand for municipal bonds, and ________ the demand for U.S. government bonds

Which of the following should be held constant when calculating an income elasticity of demand?

a. the price of the good b. prices of related goods c. tastes d. All of the above should be held constant.

For economists, substitutes for laboratory experiments often come in the form of

a. natural experiments offered by history. b. untested theories. c. "rules of thumb" and other such conveniences. d. reliance upon the wisdom of elders in the economics profession.