conditioned and the nine slope coefficients (B-values) estimated by the stepwise procedure are, in fact, correlated. In summary, we conclude that, due to intercorrelation among the nine input categories, the true role of economic motivation in the decision to relocateparticularly for nonwhites-is still an open issue. Our tests indicate that the explanatory power of the Liu Overall Index in this regard is, at best, misleading.

ECONOMISTS have suggested that differential growth in regional economy in the United States depends substantially upon labor supply, if it is assumed that the demand for a region's exports and its supply of capital are perfectly elastic.' The spatial movement of labor force or migration has been a hot subject in studies concerned with differential growth in regional income and employment. Most of these studies are concerned with a gross migration, and they always agree that employment or income consideration dominates other factors in making locational decisions among migrants.2 However, it should be noted that it is the rate of net migration (i.e., the difference of in-migration and out-migration divided by population) that directly affects the rate of labor force growth and, consequently, regional growth. Recently, more and more people have been commenting on the paradoxes of affluence. Discontent with the quality of life in the United States seems to have increased proportionally with technological advancement and growth in material wealth. Environmental quality, individual equality, economic opportunity and status, and a host of other forces that combine to shape the quality of life of the individual, are now major considerations in any public policy decisions. The primary objective of this paper is to explore the relationships between the variations in net migration rates among states and the levels of quality of life measured in those states. We first present a production model of the quality of life and some empirical results. Then follows a theoretical model, in which the decision of a household head to migrate is treated so as to maximize his quality of life. Empirical tests of the hypothesized relationship described in the migration model are contained in section IV. Concluding remarks follow.

This paper overcomes the long-standing problem of measuring motor carriers' service quality by utilizing service quality data collected from shippers. A service quality controlled cost function is estimated for a sample of less-than-truckload motor carriers. It is shown that excluding service quality variables from cost estimation significantly underestimates carriers' scale economies. These scale economies enable large carriers to offer higher quality services at competitive or even lower costs than small carriers.

PpTO date, the bulk of portfolio theory has evolved on the basis of a single-period model. Those writers who have considered sequential portfolio models, for example Tobin [24] and Mossin [19], have invariably assumed investment yields in the various periods to be stochastically independent. The purpose of this paper is to generalize the capital growth model, apparently originated by Latane [17] and Breiman [6], [7], to the case in which investment returns in one period are not statistically independent of returns in previous periods.' The assumptions employed in the present model are given in section II. Essentially, a distinction between risk due to broad market forces and risk due to individual asset factors, similar to that made by Sharpe [23] and King [16], is made. Furthermore, the no-easymoney condition is assumed to hold and the investor is required to remain solvent with probability 1. The formal model is developed in section III and section IV gives some preliminary results, including conditions for long-run growth and ultimate ruin. In section V, an optimal investment strategy is obtained on the basis of a slightly generalized and weakened version of the innocuous criterion that more is preferred to less in the very long run. The properties of the optimal strategy are discussed in section VI; it is noted that the optimal policy is myopic, that it maximizes the long-run growth rate, and that the optimal mix of assets is independent of wealth. Some concluding comments are given in section VII.

This paper examines the role of individual risk attitudes in the decision to adopt a new form of agricultural biotechnology in China. I conducted a survey and a field experiment to elicit the risk preferences of Chinese farmers, who faced the decision of whether to adopt genetically modified Bt cotton a decade ago. In my analysis, I expand the measurement of risk preferences beyond expected utility theory to incorporate prospect theory. I find that farmers who are more risk averse or more loss averse adopt Bt cotton later. Farmers who overweight small probabilities adopt Bt cotton earlier.

Using job posting wage data, we find a substantial decrease in the urban wage premium for occupations with high working-from-home (WFH) adoption following the COVID-19 pandemic, accompanied by an employment shift away from large cities. Based on a conceptual framework, the empirical findings suggest that WFH adoption lowered the productivity premium of large cities. A skill-level decomposition reveals that the urban wage premium decline was largely driven by reduced wage returns to interpersonal skills in large cities, suggesting that the reduced urban productivity premium was a result of weakened agglomeration economies due to decreased interpersonal interactions in large cities.

Prior studies show that women are more willing to accept lower wages for shorter commutes than men. We show that gender differences in commuting preferences lead to a gender wage gap only if there is a wage penalty for shortening commutes, determined by the geography of jobs. We demonstrate this by showing that the commuting and wage gaps are considerably smaller among workers living near city centers, especially for occupations with a high geographic concentration of high-wage jobs. We highlight the geography of jobs as a key force that amplifies the impact of commuting preferences on the gender wage gap.

In this paper, we study the initial-conditions problem, a complication associated with left-censored or interrupted spells in the econometric analysis of labor market transitions. In the presence of unobserved individual-specific heterogeneity, no consistent estimators have been previously constructed. This paper proposes such an estimator using indirect inference (II). The II procedure simulates the structural model and “matches” the simulated data with the actual data via the implementation of an informative auxiliary model. Consistency and asymptotic normality of the II estimator are proved. Monte Carlo experiments as well as a real data set are used to illustrate the small-sample performance of the II estimator. These results show that the II estimator is insensitive to the alternative auxiliary models chosen for the II estimation.

Developing countries face high pharmaceutical prices despite the presence of multiple generic producers. One key reason is excessive spending on sales and marketing by drug firms. This paper examines how centralized drug procurement can curb such marketing efforts and reduce prices, using a policy experiment in China where certain generics are procured through centralized auctions in pilot cities. Winning firms gain large market shares directly without high marketing costs. We find that the centralized auction significantly reduces both sales costs and prices, with winning firms experiencing notable decreases in marketing-related labor demand.