Roy's Model Research Articles

The adaptation problems of patients undergoing hemodialysis: socio-economic and clinical aspects.

OBJECTIVES: to identify adaptation problems under Roy's Model in patients undergoing hemodialysis and to correlate them with the socioeconomic and clinical aspects. METHOD: a transversal study, undertaken using a questionnaire. The sample was made up of 178 individuals. The Chi-squared and Mann-Whitney U tests were undertaken. RESULTS: the adaptation problems and the socioeconomic and clinical aspects which presented statistical associations were: Hyperkalemia and age; Edema and income; Impairment of a primary sense: touch and income; Role failure and age; Sexual dysfunction and marital status and sex; Impairment of a primary sense: vision and years of education; Intolerance to activity and years of education; Chronic pain and sex and years of education; Impaired skin integrity and age: Hypocalcemia and access; Potential for injury and age and years of education; Nutrition below the organism's requirements and age; Impairment of a primary sense: hearing and sex and kinetic evaluation of urea; Mobility in gait and/or coordination restricted, and months of hemodialysis; and, Loss of ability for self-care, and months of hemodialysis and months of illness. CONCLUSION: adaptation problems in the clientele undergoing hemodialysis can be influenced by socioeconomic/clinical data. These findings contribute to the development of the profession, fostering the nurse's reflection regarding the care.

The Generalized Roy Model and the Cost-Benefit Analysis of Social Programs

The literature on treatment effects focuses on gross benefits from program participation. We extend this literature by developing conditions under which it is possible to identify parameters measuring the cost and net surplus from program participation. Using the generalized Roy model, we nonparametrically identify the cost, benefit, and net surplus of selection into treatment without requiring the analyst to have direct information on the cost. We apply our methodology to estimate the gross benefit and net surplus of attending college.

Identifying the Distribution of Treatment Effects under Support Restrictions

The distribution of treatment effects (DTE) is often of interest in the context of welfare policy evaluation. In this paper, I consider partial identification of the DTE under known marginal distributions and support restrictions on the potential outcomes. Examples of such support restrictions include monotone treatment response, concave treatment response, convex treatment response, and the Roy model of self-selection. To establish informative bounds on the DTE, I formulate the problem as an optimal transportation linear program and develop a new dual representation to characterize the identification region with respect to the known marginal distributions. I use this result to derive informative bounds for concrete economic examples. I also propose an estimation procedure and illustrate the usefulness of my approach in the context of an empirical analysis of the effects of smoking on infant birth weight. The empirical results show that monotone treatment response has a substantial identifying power for the DTE when the marginal distributions of the potential outcomes are given.

Estimating a treatment effect under uncertainty with application to a high‐speed railway system

AbstractThis article proposes new treatment effect models and applies them to analyse the effect of high‐speed railways on population density. These models focus on the difference in treatment intensity across treated observations. The difference in treatment intensity occurs as a result of uncertainty over whether the treatment will be properly administered to observations. When evaluating large infrastructure, such as high‐speed railways, the introduction of infrastructure is considered as the treatment for municipalities. The treatment in such cases usually takes time and poses uncertainty whether it will be complete or not. To address such uncertainty, we extend the Roy model—a typical treatment effect model—under a reasonable assumption to enable it to incorporate observations that are treated but their treatment is not complete. Further, we allow the correlation between how these observations are determined and their outcomes and treatment assignments. This article also discusses the identification problem with respect to estimating model parameters. The proposed statistical models are applied to evaluate the effect of the Shinkansen, a high‐speed railway in Japan, on population density. The Canadian Journal of Statistics 42: 337–358; 2014 © 2014 Statistical Society of Canada

The Generalized Roy Model and the Cost-Benefit Analysis of Social Programs

The literature on treatment effects focuses on gross benefits from program participation. We extend this literature by developing conditions under which it is possible to identify parameters measuring the cost and net surplus from program participation. Using the generalized Roy model, we nonparametrically identify the cost, benefit, and net surplus of selection into treatment without requiring the analyst to have direct information on the cost. We apply our methodology to estimate the gross benefit and net surplus of attending college.

Financial Constraints, Endogenous Educational Choices and Self-Selection of Migrants

The Roy model predicts that migrants will be disproportionately drawnfrom the lower half of the educational distribution of the sending country if the sending country has a higher return to schooling. However, Mexican immigrants in the U.S. tend to be disproportionately drawn from the middle of the distribution. We argue that financial constraints may explain why. We study migrants' selectivity when agents that face credit constraints make joint decisions about how much to invest in education and whether to migrate. Our results show that financial constraints can explain the intermediate selection of migrants observed in the data.

A Roy Model Study of Adapting to Being HIV Positive

Roy's adaptation model outlines a generic process of adaptation useful to nurses in any situation where a patient is facing change. To advance nursing practice, nursing theories and frameworks must be constantly tested and developed through research. This article describes how the results of a qualitative grounded theory study have been used to test components of the Roy adaptation model. A framework for "negotiating uncertainty" was the result of a grounded theory study exploring adaptation to HIV. This framework has been compared to the Roy adaptation model, strengthening concepts such as focal and contextual stimuli, Roy's definition of adaptation and her description of adaptive modes, while suggesting areas for further development including the role of perception. The comparison described in this article demonstrates the usefulness of qualitative research in developing nursing models, specifically highlighting opportunities to continue refining Roy's work.

Internal Migration of Blacks in South Africa: An Application of the Roy Model

AbstractThis study investigates the internal migration of black males in South Africa over the period after the formal end of Apartheid using the 1996 census data. The two issues of our primary interests are the following: (i) whether migration patterns of black individuals are consistent with the income‐maximising hypothesis as related to the destination choice; and (ii) whether the redistribution of human capital is detected in internal migration. The results from conditional logit regressions on choices among individuals in 318 districts show that individuals prefer districts with higher expected wages, conditional on other regional characteristics. In addition, there exist differing preferences on the share of population with post‐secondary education by individuals with commensurate educational attainments. Black individuals with post‐secondary education tend to migrate into areas with a higher share of population with post‐secondary education and vice versa, which confirms the divergence of human capital levels across districts.

Problems of Sample-Selection Bias in the Historical Heights Literature: A Theoretical and Econometric Analysis

An extensive literature uses anthropometric measures, typically heights, to draw inferences about living standards in the past. This literature's influence reaches beyond economic history; the results of historical heights research appear as crucial components in development economics and related fields. The historical heights literature often relies on micro-samples drawn from sub-populations that are themselves selected: examples include volunteer soldiers, prisoners, and runaway slaves, among others. Contributors to the heights literature sometimes acknowledge that their samples might not be random draws from the population cohorts in question, but rely on normality alone to correct for potential selection into the sample. We use a simple Roy model to show that selection cannot be resolved simply by augmenting truncated samples for left-tail shortfall. Statistical tests for departures from normality cannot detect selection in Monte Carlo exercises for small to moderate levels of self-selection, obviating a standard test for selection in the heights literature. We show strong evidence of selection using micro-data on the heights of British soldiers in the late eighteen and nineteenth centuries. Consequently, widely accepted results in the literature may not reflect variations in living standards during a soldier's formative years; observed heights could be predominantly determined by the process determining selection into the sample. A survey of the current historical heights literature illustrates the problem for the three most common sources: military personnel, slaves, and prisoners.

Internal and international migration in Mexico: 1995–2000

Using micro data from Mexico and US 2000 population censuses and following a multi-choice variant of Roy's (1951) model, this article pools into one model the determinants of internal and international migration in México, while paying explicit attention to the potential problem of self-selection. The results reveal that ignoring multiple destinations in the migration decision might lead to erroneous inferences about the determinants of migration and the type of selection. After controlling for wage differences, the results suggest that single adult men with low schooling levels tend to migrate to the US while married women and men with higher levels of schooling tend to migrate within Mexico. We also found that there are strong differences between domestic and international social networks.

Redistributive Taxation in the Roy Model*

Abstract We consider optimal redistribution in a model where individuals can self-select into one of several possible sectors based on heterogeneity in a multidimensional skill vector. We first show that when the government does not observe the sectoral choice or underlying skills of its citizens, the constrained Pareto frontier can be implemented with a single nonlinear income tax. We then characterize this optimal tax schedule. If sectoral inputs are complements, a many-sector model with self-selection leads to optimal income taxes that are less progressive than the corresponding taxes in a standard single-sector model under natural conditions. However, they are more progressive than in canonical multisector economies with discrete types and without occupational choice or overlapping sectoral wage distributions.

Inference on an extended Roy model, with an application to schooling decisions in France

This paper considers the identification and estimation of an extension of Roy’s model (1951) of sectoral choice, which includes a non-pecuniary component in the selection equation and allows for uncertainty on potential earnings. We focus on the identification of the non-pecuniary component, which is key to disentangling the relative importance of monetary incentives versus preferences in the context of sorting across sectors. By making the most of the structure of the selection equation, we show that this component is point identified from the knowledge of the covariate effects on earnings, as soon as one covariate is continuous. Notably, and in contrast to most results on the identification of Roy models, this implies that identification can be achieved without any exclusion restriction nor large support condition on the covariates. As a by-product, bounds are obtained on the distribution of the ex ante monetary returns. We propose a three-stage semiparametric estimation procedure for this model, which yields root-n consistent and asymptotically normal estimators. Finally, we apply our results to the educational context, by providing new evidence from French data that non-pecuniary factors are a key determinant of higher education attendance decisions.

The Plight of Mixed-Race Adolescents

Since 1970, the fraction of mixed-race black-white births has increased nearly ninefold. This paper describes basic facts about the behaviors and outcomes of black-white mixed-race individuals. Unsurprisingly, on a host of background and achievement characteristics, as well as adult outcomes, mixed-race individuals fall in between whites and blacks. When it comes to engaging in risky and antisocial adolescent behavior, however, mixed-race adolescents are stark outliers compared to both blacks and whites. We argue that these behavioral patterns are most consistent with a two-sector Roy model, in which mixed-race adolescents, not having a predetermined peer group, engage in more risky behaviors in order to be accepted.

Immigrant Selection in the OECD*

AbstractIn this paper, we examine the determinants of educational selectivity in immigration using immigrant stock data for 70 source countries and 21 OECD destination countries, as observed in the year 2000/2001. We develop a variant of the Roy model to estimate the determinants of educational selectivity. Two key findings emerge. First, the effect of the skill premium, which is at the core of the Roy model, can be observed only after we take into account the poverty constraints operating in the source countries. Second, cultural similarities, colonial legacies, and physical distance are often more important determinants of educational selectivity than wage incentives or selective immigration policy.

Non-random dropout and the relative efficacy of escitalopram and nortriptyline in treating major depressive disorder

Most comparisons of the efficacy of antidepressants have relied on the assumption that missing data are randomly distributed. Dropout rates differ between drugs, suggesting this assumption may not hold true. This paper examines the effect of non-random dropout on a comparison of two antidepressant drugs, escitalopram and nortriptyline, in the treatment of major depressive disorder. The GENDEP study followed adult patients with major depressive disorder over 12 weeks of treatment, and the primary analysis found no difference in efficacy of the two antidepressants under missing at random assumption. By applying the recently developed Muthén–Roy model, we compared the relative efficacy of these two antidepressants taking into account non-random distribution of missing outcomes (NMAR). Individuals who dropped out of the study were those who were not responding to treatment. Based on the best fitting NMAR model, it was found that escitalopram reduced symptom scores by an additional 1.4 points on the Montgomery–Åsberg Depression Rating Scale (p = 0.02), equivalent to 5% of baseline depression severity, compared to nortriptyline. We conclude that association between dropout and worsening symptoms led to an overestimate of the effectiveness of treatment, especially with nortriptyline, in the primary analysis. These findings review the primary analysis of GENDEP and suggest that, when non-random dropout is accounted for, escitalopram is more effective than nortriptyline in reducing symptoms of major depression.

Sharp Bounds and Testability of a Roy Model of STEM Major Choices

We analyze the empirical content of the Roy model, stripped down to sector-specific unobserved heterogeneity and self-selection on the basis of potential outcomes. We characterize sharp bounds on the joint distribution of potential outcomes and testable implications of the Roy model. We apply these bounds to derive a measure of departure from Roy self-selection, so as to identify prime targets for intervention. Special emphasis is put on the case of binary outcomes. We analyze a Roy model of college major choice in Canada and Germany and take a new look at the underrepresentation of women in science, technology, engineering, and mathematics.

Identification in the Roy Model with an Application to Auctions

The paper presents conditions for non-parametric identification of a joint distribution when the marginal distributions are identified and the joint distribution is partially identified. Specifically, the paper considers the problem of estimating a J-dimensional Roy Model. The paper extends Heckman and Honore (1990) by providing an additional identification result with reasonable data requirements and without strong parametric assumptions. The result is applied to sealed bid auctions where bidders face competing auctions for substitutes, such as in auction platforms like eBay or Google Adwords.

Changes in Returns to Task-Specific Skills and Gender Wage Gap

What role did skilled-biased technological change play in narrowing the wage inequality, particularly between men and women? To answer that question this paper constructs a task-based Roy model in which workers possess a bundle of basic skills and occupations are characterized as a bundle of basic tasks. The model is estimated using the task data from the Dictionary of Occupational Titles and the PSID. The main empirical finding is that men have more motor skills than women, but the returns to motor skills have dropped significantly, accounting for a major part of the narrowed gender wage gap from 1980 to 2000. During the period of 2000-2010, the returns to motor skills were stable, but the estimates suggest that the faster growth of women's cognitive and general skills compared to men's reduced the gender wage gap.

Selection, Agriculture, and Cross-Country Productivity Differences

Cross-country labor productivity differences are larger in agriculture than in non-agriculture. We propose a new explanation for these patterns in which the self-selection of heterogeneous workers determines sector productivity. We formalize our theory in a general-equilibrium Roy model in which preferences feature a subsistence food requirement. In the model, subsistence requirements induce workers that are relatively unproductive at agricultural work to nonetheless select into the agriculture sector in poor countries. When parameterized, the model predicts that productivity differences are roughly twice as large in agriculture as non-agriculture even when countries differ by an economy-wide efficiency term that affects both sectors uniformly. (JEL J24, J31, J43, O11, O13, O40)

Selection, Agriculture and Cross-Country Productivity Differences

Cross-country labor productivity differences are larger in agriculture than in non-agriculture. We propose a new explanation for these patterns in which the self-selection of heterogeneous workers determines sector productivity. We formalize our theory in a general equilibrium Roy model with preferences featuring a subsistence food requirement. In the model, subsistence requirements induce workers that are relatively unproductive at agriculture work to nonetheless select into the agriculture sector in poor countries. When parameterized, the model predicts that agriculture productivity differences are twice as large as those in non-agriculture even when economies differ by an economy-wide efficiency term that affects both sectors uniformly.