Zhuo Chen

Geographically weighted regression bandwidth selection and spatial autocorrelation: an empirical example using Chinese agriculture data

Seong-Hoon Cho et al. — Thu, 03 Jun 2010 06:02:47 PDT

This research note examined the performance of Geographically Weighted Regression (GWR) using two calibration methods. The first method, Cross Validation (CV), has been commonly used in the applied literature using GWR. A second criterion selected an optimal bandwidth that corresponded with the smallest spatial error Lagrange Multiplier (LM) test statistic. We find that there is a tradeoff between addressing spatial autocorrelation and reducing degree of extreme coefficients in GWR. Although spatial autocorrelation can be controlled for by using the LM criterion, a substantial degree of extreme coefficients may remain. However, while the CV approach appears to be less prone to producing extreme coefficients, it may not always attend to the problems that arise in the presence of spatial error autocorrelation

Explaining Production Inefficiency in China’s Agriculture Using Data Envelopment Analysis and Semi-Parametric Bootstrapping

Daneil Monchuk et al. — Wed, 28 Apr 2010 12:39:00 PDT

In this paper we examine more closely the factors associated with production inefficiency in China's agriculture. The approach we take involves a two-stage process where output efficiency scores are first estimated using data envelopment analysis, and then in the second stage, variation in the resulting efficiency scores is explained using a truncated regression model with inference based on a semi-parametric bootstrap routine. Among the results we find that a heavy industrial presence is associated with reduced agricultural production efficiency and may be an indication that externalities from the industrial process, such as air and ground water pollution, affect agricultural production. We also find evidence that counties with a large percentage of the rural labor force engaged in agriculture tend to be less efficient, and suggests that nurturing and promoting growth of non-primary agriculture may lead to more efficient use of labor resources in agriculture.

Urban Growth Boundary and Housing Prices: The Case of Knox County, Tennessee

Seong-Hoon Cho et al. — Mon, 01 Mar 2010 16:20:50 PST

This study tests the hypothesis that a higher present value of expected rental stream of undeveloped land in the urban growth area influences the effect of the Urban Growth Boundary (UGB) on the values of newly developed houses in Knoxville and Knox County, Tennessee. We estimate a version of the Box-Cox (BC) transformed hedonic housing price model, which accommodates both non-normality and heteroskedasticity in the stochastic error term. The finding of this study verifies the premise that the values of newly developed houses after the implementation of a UGB are likely to be higher within the urban growth area than those outside, all other things equal.

Examining the Role of Gender in Career Advancement at the Centers for Disease Control and Prevention

Zhuo Chen et al. — Fri, 19 Feb 2010 09:09:47 PST

During the past decade, efforts to promote gender parity in the healing and public health professions have met with only partial success. We provide a critical update regarding the status of women in the public health profession by exploring gender-related differences in promotion rates at the nation's leading public health agency, the Centers for Disease Control and Prevention (CDC). Using personnel data drawn from CDC, we found that the gender gap in promotion has diminished across time and that this reduction can be attributed to changes in individual characteristics (e.g., higher educational levels and more federal work experience). However, a substantial gap in promotion that cannot be explained by such characteristics has persisted, indicating continuing barriers in women's career advancement.

The Impact of Minimum Wage Rates on Body Weight in the United States

David O. Meltzer et al. — Mon, 09 Nov 2009 09:03:06 PST

Growing consumption of increasingly less expensive food, and especially “fast food”, has been cited as a potential cause of increasing rate of obesity in the United States over the past several decades. Because the real minimum wage in the United States has declined by as much as half over 1968-2007 and because minimum wage labor is a major contributor to the cost of food away from home we hypothesized that changes in the minimum wage would be associated with changes in bodyweight over this period. To examine this, we use data from the Behavioral Risk Factor Surveillance System from 1984-2006 to test whether variation in the real minimum wage was associated with changes in body mass index (BMI). We also examine whether this association varied by gender, education and income, and used quantile regression to test whether the association varied over the BMI distribution. We also estimate the fraction of the increase in BMI since 1970 attributable to minimum wage declines. We find that a $1 decrease in the real minimum wage was associated with a 0.06 increase in BMI. This relationship was significant across gender and income groups and largest among the highest percentiles of the BMI distribution. Real minimum wage decreases can explain 10% of the change in BMI since 1970. We conclude that the declining real minimum wage rates has contributed to the increasing rate of overweight and obesity in the United States. Studies to clarify the mechanism by which minimum wages may affect obesity might help determine appropriate policy responses.

Factors associated with differences in mortality and self-reported health across states in the United States

Zhuo Chen et al. — Fri, 30 Oct 2009 08:35:33 PDT

Objective Recent studies indicate continuing health disparities across geographic units in the US. This paper provides updated estimates of the association between socioeconomic factors and population health using a new state-level dataset and panel econometric methods that account for state-specific effects and autoregressive error structure.

Methods Data from multiple sources for the 50 US states and the District of Columbia are merged. The dependent variables are age-adjusted all-cause mortality, self-assessed health status, and number of healthy days. Panel econometric models are used to accommodate state-specific unobserved factors and to incorporate autoregressive random disturbances to provide consistent and robust estimates.

Results A 1-unit increase in the number of physicians per 1000 population is associated with a reduction in mortality by 30/100,000. The effects of physician-to-population ratio on self-reported health measures are mixed. Socioeconomic, demographic, as well as the prevalence of smoking and obesity have varying effects on mortality and self-reported measures of health.

Conclusions The new estimate of the association between physician supply and lower mortality suggests continuing efforts to assess the need for policies and incentives to induce physician labor supply in underserved states. Strategies and policies to reduce health disparities should address social, economic and individual risk factors.

Economic Perspective on Strategic Human Capital Management and Planning for the Centers for Disease Control and Prevention

Carol A. Gotway Crawford et al. — Fri, 30 Oct 2009 08:25:57 PDT

An organization's workforce-or human capital-is its most valuable asset. The 2002 President's Management Agenda emphasizes the importance of strategic human capital management by requiring all federal agencies to improve performance by enhancing personnel and compensation systems. In response to these directives, the Centers for Disease Control and Prevention (CDC) drafted its strategic human capital management plan to ensure that it is aligned strategically to support the agency's mission and its health protection goals. In this article, we explore the personnel economics literature to draw lessons from research studies that can help CDC enhance its human capital management and planning. To do so, we focus on topics that are of practical importance and empirical relevance to CDC's internal workforce and personnel needs with an emphasis on identifying promising research issues or methodological approaches. The personnel economics literature is rich with theoretically sound and empirically rigorous approaches for shaping an evidence-based approach to human capital management that can enhance incentives to attract, retain, and motivate a talented federal public health workforce, thereby promoting the culture of high-performance government.

Perspectives on Public Health Workforce Research

Carol A. Gotway Crawford et al. — Fri, 30 Oct 2009 08:22:10 PDT

The Centers for Disease Control and Prevention Office of Workforce and Career Development is committed to developing a competent, sustainable, and diverse public health workforce through evidence-based training, career and leadership development, and strategic workforce planning to improve population health outcomes. This article reviews the previous efforts in identifying priorities of public health workforce research, which are summarized as eight major research themes. We outline a strategic framework for public health workforce research that includes six functional areas (ie, definition and standards, data, methodology, evaluation, policy, and dissemination and translation). To conceptualize and prioritize development of an actionable public health research agenda, we constructed a matrix of key challenges in workforce analysis by public health workforce categories. Extensive reviews were conducted to identify valuable methods, models, and approaches to public health workforce research. We explore new tools and approaches for addressing priority areas for public health workforce and career development research and assess how tools from multiple disciplines of social sciences can guide the development of a research framework for advancing public health workforce research and policy.

Lifestyles, Demographics, Dietary Behavior, and Obesity: A Switching Regression Analysis

Steven T. Yen et al. — Mon, 20 Jul 2009 13:42:13 PDT

Objectives. To investigate the effects of lifestyles, demographics, and dietary behavior on overweight and obesity. Data Source. Continuing Survey of Food Intakes by Individuals 1994-1996, U.S. Department of Agriculture. Study Design. We developed a three-regime switching regression model to examine the effects of lifestyle, dietary behavior, and sociodemographic factors on body mass index (BMI) by weight category and accommodating endogeneity of exercise and food intake to avoid simultaneous equation bias. Marginal effects are calculated to assess the impacts of explanatory variables on the probabilities of weight categories and BMI levels. Principal Findings. Weight categories and exercise are found to be endogenous. Lifestyle, dietary behavior, social status, and other sociodemographic factors affect BMI differently across weight categories. Education, employment, and income have strong impacts on the likelihood of overweight and obesity. Exercise reduces the probabilities of being overweight and obese and the level of BMI among overweight individuals. Conclusion. Health education programs can be targeted at individuals susceptible to overweight and obesity. Social status variables, along with genetic and geographic factors, such as region, urbanization, age, and race, can be used to pinpoint these individuals.

Farm Technology and Technical Efficiency: Evidence from Four Regions in China

Zhuo Chen et al. — Thu, 04 Jun 2009 13:29:32 PDT

In this paper we fit stochastic frontier production functions to data of Chinese farms grouped into each of four regions—North, Northeast, East, and Southwest—over 1995–1999. These frontier production functions are shown to have statistically different structures, and the elasticities provide some evidence of diminished marginal products of chemical inputs in the East and capital services in the North and Southwest. Labor has a low elasticity except in the North. Standardized technical efficiency scores are estimated for the farms and are shown to have the same structure across regions and to be related to the age of the household head, land fragmentation, and the village migration ratio, controlling for year effects and village or regional fixed effects.

Guest Editors’ Introduction to the Thematic Issue on Family Economic Issues in Developing and Transition Economies

Zhuo Chen et al. — Fri, 03 Apr 2009 13:47:20 PDT

Forecasting Housing Prices under Different Market Segmentation Assumptions

Zhuo Chen et al. — Fri, 03 Apr 2009 13:41:00 PDT

Three types of market segmentation strategies are available to estimate hedonic housing price models—i.e. no segmentation, segmentation by using statistical clustering methods and segmentation by using a priori information. This research tests the hypothesis of Tiebout theory that individual residential decision-making is determined by equilibrium provision of local public goods in accord with the tastes and preferences of residents, thereby sorting their housing locations into optimal sub-markets. Forecasting accuracies of eight sub-market segmentation strategies and two forecast-combining methods are examined by using housing sales data from Knox County, Tennessee, USA. The results provide empirical support for Tiebout theory of optimal housing sub-market location in that boundaries drawn using a priori information from local government jurisdictions, school districts and expert opinions are more closely aligned with the equilibrium provision of local public goods than boundaries drawn by statistical clustering methods. The advantage of forecast-combining is also demonstrated.

Efficiency and technology gap in China's agriculture: A regional meta-frontier analysis

Zhuo Chen et al. — Fri, 03 Apr 2009 13:24:54 PDT

This paper utilizes a unique county-level dataset to examine technical efficiency and technology gap in China's agriculture. We classify the counties into four regions with distinctive levels of economic development, and hence production technologies. A meta-frontier analysis is used. We find that although the eastern counties have the highest efficiency scores with respect to the regional frontier but the northeastern region leads in terms of agricultural production technology nationwide. Meanwhile, the mean efficiency of the northeastern counties is particularly low, suggesting technology and knowledge diffusion within region might help to improve production efficiency and thus agricultural output.

Calculating concentration index with repetitive values of indicators of economic welfare

Zhuo Chen et al. — Fri, 03 Apr 2009 13:22:06 PDT

Repetitive values of the ranking indicators of economic welfare are often introduced due to incidental ties or censoring in the welfare variable, or the categorical nature of welfare variables used in numerous national surveys. In calculating concentration index (CI), assigning different fractional ranks to observations that have same values of the welfare measure leads to unstable and inconsistent CI estimates when the welfare variable is categorical or censored. In this paper, we establish an interval within which the CI estimates lie, and propose a solution, which is an extension of (Kakwani, N.C., Wagstaff, A., van Doorslaer, E., 1997. Socioeconomic inequalities in health: measurement, computation, and statistical inference. Journal of Econometrics 77, 87–103), for consistent and replicable estimates of CI when there are a substantial number of ties of the welfare indicator.

Prevention Effectiveness

Kakoli Roy et al. — Fri, 03 Apr 2009 13:17:40 PDT

Beefing up with the Chans: Evidence for the effects of relative income and income inequality on health from the China Health and Nutrition Survey

Zhuo Chen et al. — Thu, 01 May 2008 17:19:36 PDT

A great deal of research has examined the hypothesis that the well-being of individuals is shaped not just by the absolute level of resources available to them but also the level of resources available to them relative to others in their cohort or community. Several causal pathways have been hypothesized to explain associations between relative social position and health. For example, greater community income could increase the overall availability of health care in a community or decrease the availability for people for any given level of individual income. Relative social position could also create stress, resulting in adverse health outcomes through increased hypertension and other pathways.

We explore yet another pathway by which relative social position may affect health. Specifically, to the extent that norms about physical appearance might be shaped by one's observations of others, we examine whether obesity might constitute another physiologic pathway by which community attributes could influence aspects of individual health, such as hypertension. We examine this hypothesis in rural China, where income often limits food intake so that, if community norms are an important determinant of individual obesity, higher community income could increase the obesity rate in a community and therefore change norms about obesity. These norms, in turn, could increase individuals' chances of being obese given their income.

To test this hypothesis, we use multilevel linear probability models to examine the relationship between ecologic factors, i.e., relative income and income inequality, and health risk factors, i.e., obesity and hypertension among a sample of Chinese adults interviewed in four waves over 9 years. The results suggest that, among rural Chinese residents, increasing community average income and income inequality are positively associated with both obesity and hypertension. However, the effect of relative income on hypertension is not accounted for by increases in obesity. We did not find a strong relationship between socioeconomic conditions and the health risk factors among urban residents, where norms might be likely to be less strongly influenced by local attributes. Hence, the present study provides evidence supporting the hypothesis that relative income and income inequality affect obesity and hypertension, but no evidence that the effects on hypertension operated through effects on obesity.

Technical notes for "calculating concentration index with repetitive values of the welfare variable"

Zhuo Chen et al. — Tue, 29 Apr 2008 08:12:36 PDT

This technical note provides the proof of Theorem 1 in “Calculating concentration index with repetitive values of the welfare variable” by Chen and Roy (2008).

Food Stamp Program Participation and Food Insecurity: An Instrumental Variables Approach

Steven T. Yen et al. — Sun, 06 Apr 2008 08:35:50 PDT

The relationship between Food Stamp Program (FSP) participation and household food insecurity (FI) is investigated using data from the 1996–1997 National Food Stamp Program Survey. Endogeneity of FSP participation is accommodated with an instrumental variables approach. In contrast to other findings reported in the literature, results suggest participation in the FSP reduces the severity of FI. Sociodemographic variables play important roles in FSP participation and FI. Underreporting of FSP participation and limited observations of food-insecure households in previous studies may have also been factors.

CONCINDC: Stata module to calculate concentration index with both individual and grouped data

Zhuo Chen — Tue, 18 Sep 2007 18:51:01 PDT

oncindc computes the concentration index (CI) for micro data with a categorical welfare variable or grouped data. See Kakwani, Wagstaff and van Doorslaer (1997). Note that although it was originally designed for microdata with a categorical welfare variable, it can handle grouped data and microdata with actual (not categorical) welfare variable. They could be treated as a special case of microdata with categorical welfare measure: there is only one observation for each category. For grouped data, since the program can handle frequency weight, the group sizes can essentially be treated as frequency weights. The program also can use standard error of group means of the health outcome if supplied. If not, it will be estimated as the standard deviation of health outcomes.

The effects of urban sprawl on body mass index: where people live does matter

Seong-Hoon Cho et al. — Tue, 18 Sep 2007 18:49:47 PDT

This study examined the effects of urban sprawl on body weights among U.S. adults using quantile regression that is less sensitive to outliers and the skewed distribution of body weights. Significant variations in the effects of urban sprawl on different levels of body weights were found. Holding all other variables constant, the body mass index of the 25% quantile in Harvey County, KS is 1.01 kg/m2 higher than that of the 25% quantile in New York County, NY while the difference is much larger, 1.75 kg/m2 in the 75% quantile. However, urban sprawl has no significant effect on individuals at the 95% quantile. Consumer policy implications are discussed.