The residual market factor,the APT,and mean-variance efficiency

The rapidly increasing volume of both published and unpublished work on the arbitrage pricing theory (APT) of Ross (1976) has given rise to a number of misunderstandings at the interface of theoretical and econometric work. In this article we extend the theoretical structure of our previous work (McElroy and Burmeister, 1985, 1988; Burmeister and McElroy, 1987, 1988) to provide a broad yet rigorous framework both for econometric estimation and for better economic interpretation of new empirical results. We begin with the case where allK factors are observed, and then present the second case ofK−1≡J observed APT factors and one unobserved factor, theresidual market factor introduced in McElroy and Burmeister (1985). The economic interpretations for equivalent specifications of this model are discussed, and we enumerate several immediate payoffs to these specifications. The main new results are concerned with the sometimes intricate relationships among APT models withK factors and APT models withK factors that are constrained to satisfy mean-variance efficiency restrictions. These results are not only of theoretical interest, but more importantly they provide the basis for econometric estimation and testing of nested hypotheses. These econometric issues are discussed in detail.     

Has the United States Overinvested in Housing?

Several economists have concluded that housing investment has been excessive relative to industrial investment in the U.S. Most blame provisions of the federal income tax that favor owner-occupied housing.
This paper poses the question within a two-sector neoclassical growth model which permits the social return to housing to differ from that to non-housing. The model is estimated using national income accounts and capital stock data from 1929 to 1983. The conclusion is that the return to housing capital is about half that to non-housing capital and that the housing stock should be about 75% of its 1983 volume.     

OPTIMAL RULES FOR PATENT RACES*

There are two important rules to patent races: minimal accomplishment necessary to receive the patent and the allocation of the innovation benefits. We study the optimal combination of these rules. A planner, who cannot distinguish between competing firms in a multistage innovation race, chooses the patent rules by maximizing either consumer or social surplus. We show that efficiency cost of prizes is a key consideration. Races are undesirable only when efficiency costs are low, firms are similar, and social surplus is maximized. Otherwise, the optimal policy involves a race of nontrivial duration to spur innovation and filter out inferior innovators.