Golcuk for normal good: a good characterized by a positive relationship between purchases of that good and changes in consumer income. normative economics: economic analysis that explains or predicts outcomes on the basis of moral judgements, opinions, or beliefs. Okun’s Law: an observed negative relationship between changes in unemployment and national output which states that a one percentage point decrease in the unemployment rate is associated with a 2 to 2.5 percent increase in real GDP. oligopoly: an industry consisting of a few large firms and fairly high barriers to entry. Oligopolistic firms are often characterized as being mutually interdependent, which implies that strategic interaction may exist within oligopolistic industries. opportunity cost: the implicit cost of producing or consuming additional units, expressed in terms of what was given up to obtain those additional units (i. Golcuk 2016.