Russell's study compared gpa of those students who volunteered for academic study skills training and those who did not elect to take the training. he found that those who had the training also had higher gpa. with which validity threat should russell be most concerned?

Which of the following would cause a shift to the right of the supply curve for gasoline? i. a large increase in the price of public transportation. ii. a large decrease in the price of automobiles. iii. a large reduction in the costs of producing gasoline

Alaska king crab fishing in the 1960s and '70s was a dangerous but rich fishery. boats from as far away as california and japan braved the treacherous gulf of alaska crossing to reach the abundant king crab beds in cook inlet and bristol bay. suddenly, in the early 1980s, the fishery crashed due to over fishing. all crabbing in those areas ended. to this day, there is no crabbing in bristol bay or cook inlet. a. how would an economist explain the decline of the alaska king crab fishery

Suppose life expectancy in years (l) is a function of two inputs, health expenditures (h) and nutrition expenditures (n) in hundreds of dollars per year. the production function is upper l equals ch superscript 0.40 baseline upper n superscript 0.60l=ch0.40n0.60. beginning with c = 1, a health input of $400400 per year (hequals=44) and a nutrition input of $400400 per year (nequals=44), show that the marginal product of health expenditures and the marginal product of nutrition expenditures are both decreasing. the marginal product of health expenditures when h goes from 44 to 55 is nothing, and the marginal product of health when h goes from 66 to 77 is nothing. (round your answers to three decimal places.)