The test statistic used to test the hypothesis of whether a regression coefficient is significantly different from zero, holding all other independent variables constant, is called a(n):

Suppose that in 2013, all prices in the economy increased by 50% and that all wages and salaries also increased by 50%. In 2013, you were

A) better off than you were in 2012 as your salary was higher than it was in 2012 and you could buy more goods and services. B) worse off than you were in 2012 as you could no longer afford to buy as many goods and services. C) no better off or worse off than you were in 2012 as the purchasing power of your salary remained the same. D) The purchasing power of your salary cannot be determined with the given information, so you cannot determine if you were better off or worse off in 2013 than in 2012.

In which market structures is there product differentiation?

A) perfect competition and monopolistic competition B) monopolistic competition and oligopoly C) oligopoly and monopoly D) perfect competition and monopoly