For a third variable to be plausible as the explanation in an established association, the third variable must be related to both of the measured variables in the original association.

3. The invisible hand refers to   .    

Joseph H. Glidden and I.L. Ellwood developed and marketed barb wire.

 As a nation’s average education level increases, the nation’s level of productivity  

4. Ceteris paribus, if the opportunity cost of purchasing a good rises, then the maximum price a particular consumer is willing to pay for that good            

If the government places a price ceiling on cancer-treating drugs, then            

19. A labor-intensive production process is one that             

Author of the Little Women series about an ambitious girl who fought conventional society to become a writer.

The basic dividend-discount model is a bit of an oversimplification for valuing stocks because it:  

In 1890, at Wounded Knee, South Dakota,