Knowledge that Transforms

This analysis develops a model in which, for the first time, households' mobility decisions are separated into intra-urban movements and migrations. These two mobility decisions and the households' tenure (own/rent) choice are estimated as part of a multinomial logit framework and are found to be jointly determined. The literature suggests that the intra-urban mobility and migration decisions are motivated by quite different factors. Consequently, by separating the two choices for the purpose of estimation, each equation can be specified more correctly. In addition, variables which affect migration can be shown to have an impact on intra-urban mobility and tenure choice which would otherwise be ignored. Copyright 1991 by MIT Press.

This study finds that a strong bibliometric regularity exists in the publication pattern in the economics literature; the number of authors publishing n papers is approximately 1/n(superscript "c") of those publishing one paper. The economics literature conforms very well to the model with c = 1.84 if data are taken from a large collection of journals. When applied to individual journals, the result shows that values of c range from 2.04 to 3.11. This paper also reports the degree of author concentration among leading economics journals. Finally, this study finds that the graduates of three graduate programs account for more than half of the top 100 authors, indicates strong institutional dominance in the production of the most prolific authors. Copyright 1991 by MIT Press.

The authors use Census-based data on the state distribution of the undocumented-alien population in analyzing the relationship between that population and unemployment among youth and minority workers. Regression results from their two-equation models do not support commonly expressed fears that undocumented immigration has caused any substantial increases in joblessness among these presumably vulnerable groups, although small amounts of displacement are indicated. A sizable reverse effect is evident: undocumented immigrants tend to concentrate in states where labor markets for these marginal groups are most favorable. Copyright 1991 by MIT Press.

Numerous studies have confirmed the importance of habit formation, as represented by a lagged dependent variable, in demand analysis. Although all work to date has been based on aggregate time series data, this study uses household level BLS Interview Panel data to test the habit hypothesis. An interrelated demand system for seventeen goods is estimated from cross-section data and compared with a similar system based on time series data. The results show that the habit component is significantly different between the two data sets and much smaller in the cross-section data. Habit effects, while not as large in cross-section data as time series, are still highly significant. Several explanations are offered concerning why the two sets of estimates differ. Copyright 1991 by MIT Press.

Consumption (Economics); Income

This study investigates the stability of long-run log-linear demand functions for narrowly defined monetary aggregates (M1, Monetary Base) in the U.S. during the post World War II period. The hypotheses that the individual time series which appear in such equations (real M1, real Monetary Base, real Personal Income and short-term and long-term nominal interest rates) all have unit roots cannot be rejected. The primary conclusion of this study is that with proper attention to the time series properties of the available data, there exists strong evidence in support of a stable equilibrium demand function for real balances in the post-World War II U.S. economy. The hypothesis of a unitary equilibrium real income elasticity (a velocity function) cannot be rejected. Further, the estimates of equilibrium interest elasticities are approximately -.5 to -.6 for real M1 and -.4 to -.5 for real monetary base. The estimated interest elasticities are significantly different statistically depending on whether long- term or short-term interest rates are used, but the observed differences in these estimates are not of economic significance.

Previous research examining the nonemployment of displaced workers suffers from methodological flaws which reinforce widely held but substantially incorrect views about the pattern of postseparation joblessness. In particular, adjustment difficulties have been overstated for nonwhites, long tenure workers, and those terminated during periods of high unemployment and underestimated for persons in manufacturing industries or white collar occupations.

The effect of health-plan membership on the utilization of health-care services is of interest to both consumers and policymakers. Often estimation of that effect is difficult because data are nonexperimental and the dependent variable exhibits a high proportion of zeros. The authors propose a model of utilization that addresses both problems. After controlling for chronic illness and other observed variables, they find no evidence of further selectivity bias in equations for physician contacts and inpatient days. The authors' estimates of the effect of health-plan membership on utilization of services are similar to those from experimental data. Coauthors are Roger Feldman, Steven Cassou, and Michael Finch. Copyright 1991 by MIT Press.

This paper analyzes the search decision of employees empirically. A maximum likelihood model consisting of a wage equation and a search equation, in which the difference between the present and the nonobserved alternative (market) wage is included, is estimated to investigate the importance of nonwage job characteristics and future wage prospects relative to the present wage. The estimation results indicate that both present and future wages and nonwage job characteristics have a significant impact on the search decisions of employees. Copyright 1991 by MIT Press.

This study presents an econometric examination of the joint decisions of farmers on the adoption of a microcomputer and (or) purchased computers services. The characteristics of a farmer--schooling, age, off-farm work--are shown to be important variables for explaining the odds of adopting purchased computers services only, a microcomputer only, and both computer technologies. Adoption of computer technologies seems to occur in farming operations where they can be expected to greatly enhance the efficiency. Copyright 1991 by MIT Press.