Variation In Hours Research Articles

The Way to Wealth and the Way to Leisure: The Impact of College Education on Graduates’ Earnings and Hours of Work

This study extends the analysis of the economic return of college education up to 10 years after college education and further examines the impact of college education on graduates’ hours of work. The results suggest that variation in hours of work explains a portion of earnings differentials among college graduates. Graduates from high-quality private institutions tend to work longer hours than their peers from other types of institutions. Female graduates spend fewer hours working than their male counterparts. As far as family background is concerned, graduates from high-income families tend to work longer hours and first-generation college graduates tend to work fewer hours. Finally, business majors seem to work longer hours while health and public affair majors less hours.

Labor Supply Decisions of Rural Low-Income Mothers

Labor force participation is crucial to the economic well-being of low-income rural families. This study identified the factors that influence two decisions that low-income rural mothers make regarding their employment: labor force entry and number of hours supplied to employment. The sample consisted of 412 rural low-income mothers who participated in a multi-state study. The logistic regression model correctly predicted 80 percent of their work participation decisions. Employed rural mothers appeared to be older, better educated, and less likely to suffer from depression compared to those not working. Additionally, they were more likely to have an employed partner, a driver’s license, child care assistance, and Earned Income Tax Credit from the previous year. The estimated labor supply function explained 33 percent of the variation in hours worked by the 208 employed rural mothers. Higher wages, availability of health insurance, and overtime benefits predicted the number of hours that these employed mothers were willing to work.

Long-Term Changes in Labor Supply and Taxes: Evidence from OECD Countries, 1956-2004

We document large differences in trend changes in hours worked across OECD countries over the period 1956-2004. We then assess the extent to which these changes are consistent with the intratemporal first order condition from the neoclassical growth model. We find large and trending deviations from this condition, and that the model can account for virtually none of the changes in hours worked. We then extend the model to incorporate observed changes in taxes. Our findings suggest that taxes can account for much of the variation in hours worked both over time and across countries.

Changes in women's hours of market work: The role of returns to experience

Over the past several decades, married women's hours of market work increased significantly in the US. I argue that changes in behavior by married women with children account for much of this change. In particular, the pattern of married women's work hours has changed substantially over the life cycle. In the past, married women in childbearing age tended to specialize in childrearing and home production activities at the expense of engaging in market work. Now they do not curb the hours they work in the market. What factors contribute to this change in behavior? In this paper, I focus on relative changes in returns to experience as an explanation. I use PSID data for the 1970s and the 1990s to estimate the extent to which relative returns to experience have changed. I then use a life-cycle model with human capital accumulation and home production to quantitatively assess the consequences of this increase for married women's hours of work over the life cycle. The estimates of the human capital production function show that women's marginal returns to experience increased by 25% across decades, whereas men's increased by only 6%. I show that this relative change accounts for 96% of the observed variation in married women's hours of work. Moreover, according to the model, the increase in returns to experience accounts for roughly half of the increase in the female/male wage ratio that is found in the data. I also show that a decline in the gender wage gap, holding returns to experience constant, accounts for only 18% of the total increase in hours of work. As a consequence, it cannot explain the change in the shape of women's life-cycle profiles. Although the focus of the analysis is the labor supply behavior of women, the model also allows predictions about the behavior of men and single women. These predictions are consistent with the data.

Musculoskeletal disorders of the upper extremity associated with computer work: A systematic review

The epidemiological literature is critically reviewed to evaluate the evidence supporting a causal relationship between computer work and musculoskeletal symptoms and disorders (MSDs) of the hand, wrist, forearm, and elbow. Since 1990, 33 publications were found that met the selection criteria –11 were prospective in design and 22 were cross-sectional. All prospective studies that measured extent of computer use found a positive association between computer work and upper extremity musculoskeletal symptoms. The two prospective studies to conduct physical examinations both found a relationship between hours of computer use and increased risk of upper extremity diagnoses. Of the 22 cross-sectional studies, 17 studies found positive associations. Two of the five studies reporting no association found increased risks of certain disorders under certain combinations of computer use and other factors. The remaining three studies were limited by either a small sample size or low variation of computer use hours within the study population. We conclude that there is consistent evidence of a positive relationship across numerous prospective and cross-sectional studies with increased risk most pronounced beyond 20 hours/week of computer use or with increasing years of computer work. The disorders confirmed with physical examinations are wrist tendonitis and tenosynovitis, medial and lateral epicondylitis, and DeQuervain's tenosynovitis. The risk of carpal tunnel syndrome is increased with use of a computer, especially with mouse use for more than 20 hours per week.

Inter-household variation in adoption of cash cropping and its effects on labor and dietary patterns: a study in a Li hamlet in Hainan island, China

Following the economic development policy of China since the 1980s, the indigenous food production systems of communities have been transformed to a market economy. The introduction of cash crops has been the major developmental policy of China’s rural areas. Despite the overall improvement of economic status among farmers over the last two decades, inequality among households has emerged as a new problem. In the present study, we investigated the process of how cash crops were accepted in a Li hamlet in Hainan island, China, and how this has influenced the labor and dietary patterns of people. In examining this process, we focussed on inter-household differences. We also reconstructed the demographic changes and land use patterns of all the households of the hamlet for the period between 1985 and 2004. Data on labor and diet of 11 representative households were collected by direct measurement/observation from a total of 12 months of fieldwork in 2000–2004. Reconstruction of the adoption process revealed two important factors that might contribute to current variation among households: (1) the success of pioneering households, which played an important role in triggering the hamlet-level adoption of cash crops, and (2) the availability of labor resources during 1995–2004, which explains the inter-household variation observed in 2004. The households that succeeded in cash cropping appeared to be able to afford further investment in cash cropping, which may have further enlarged inter-household variation. Inter-household variation in cash cropping in 2004 partly explains inter-household variation in food consumption and labor hours. The intensification and maintenance of rice cultivation may alleviate the nutritional (initial phase) and work burden posed by the adoption of cash cropping.

A Field-Based Analysis of Audit Workpaper Review

This paper applies the models of Gibbins and Trotman (2002) and Rich et al. (1997a) in a public sector environment. We consider the factors impacting extent of review, level of stylization, and reviewer styles. We also examine the impact of reviewer rank on the above. In a field-based study we found that variation in review hours was due to both individual reviewer factors (reviewer style) and contextual factors (company size, time pressure, attitude of the reviewer to detail). Overall these results support the general robustness of the Gibbins and Trotman (2002) model to a public sector environment involving very experienced seniors and managers. Following the Rich et al. (1997a) framework we also provide evidence on the extent and types of stylization in the review process. Seniors and managers believed that the focuses of different reviewers differed substantially and that they stylized both the presentation and content of the working papers to accommodate these differences. While the evidence on their stylization was strong, their awareness of stylization by preparers for them was weaker. We also found significant differences between senior and manager reviewers including their extent of review, expectations of the perceived emphasis of the review level above, relative time spent on opinion formation and documentation, and the extent of their responses to reviewers' preferences. Finally, we provided a range of additional insights into reviewer style.

Undergraduate orthodontic teaching in UK dental schools

This paper assesses the current teaching of undergraduate orthodontics in UK dental schools and the changes these courses have undergone in the last three years. Questionnaires were e-mailed to the undergraduate orthodontic course leaders in each of the UK dental schools. Twelve dental schools agreed to participate in the survey. Responses were checked for completeness, summarised and sent back to individual course leaders to verify. These verified responses were then analysed. There was a wide variation in the orthodontic course form and content in the 12 UK dental schools. The greatest variation occurred in the clinical teaching hours (50 to 126), the types of patient treatment undertaken (removable only to full fixed), the laboratory teaching hours (0 to 60), the content of the laboratory course (removable appliances to fixed appliance typodonts), the in-course assessment (minimal to extensive, and 0% to 40% of BDS), and the format of the BDS examination. A number of dental schools reported reductions in their orthodontic courses in academic, clinical and laboratory hours and content, and in the number of undergraduate orthodontic teaching staff in the last three years. Comparison of undergraduate orthodontic courses revealed a wide variation in course hours and content, and in student assessment and examination. Considerable changes have occurred to the courses in the last three years. Half of the UK courses have been affected by The First Five Years General Dental Council document(1) and university pressures, with reductions in both course content and staffing in the last three years. For standards to be maintained, guidelines are needed to safeguard clinical content and student assessment in undergraduate orthodontic courses in UK dental schools.

Organisation du travail dans des élevages familiaux lait et viande sur un front pionnier amazonien au Brésil. Etude à partir de sept enquêtes « bilan travail »

Cette étude privilégie un regard nouveau sur les élevages laitiers familiaux en frontière agricole au Brésil : l’organisation technique du travail. Le travail apparaît être un facteur essentiel des conduites d’élevage et une contrainte aux transformations durables des exploitations. Cependant très peu de connaissances ont été produites jusqu’à ce jour. Pour rendre compte de l’organisation du travail sur une année, les temps de travaux ont été quantifiés et les collectifs de travail décrits dans sept fermes « lait-viande », à partir de la méthode « bilan travail ». Les mêmes activités d’astreinte avec le troupeau laitier ont été réalisées dans tous les élevages avec des variances quant aux volumes horaires : 1 h 45 à 6 h 30 par jour et par personne de la cellule de base. Les différences entre les fermes ont été liées à la composition de la cellule de base, à l’effectif de vaches traites et au mode de commercialisation du lait. Sur l’année, 17 à 328 journées ont été dédiées aux activités de saison, dont 17 à 176 jours sur les prairies cultivées. Une partie des activités sur les prairies (sarclage, implantation, clôtures) ont été déléguée à de l’aide familiale ou à des salariés temporaires. Trois stratégies d’éleveurs face au travail ont été identifiées, reposant sur la simplification des conduites ou l’organisation des collectifs de travail. L’étude conclut que le travail est un facteur à prendre en compte pour appuyer la transformation des pratiques des éleveurs et la durabilité des élevages familiaux amazoniens. Les futures actions de recherche-développement en Amazonie permettront de produire des connaissances pour identifier les voies d’amélioration possibles.

Labor Supply Shifts and Economic Fluctuations

We investigate the role of labor-supply shifts in economic fluctuations. A new VAR identification scheme for labor supply shocks is proposed. According to our VAR analysis of post-war U.S. data, labor-supply shifts account for about half the variation in hours and one-fifth of variation in aggregate output. To assess the role of labor-supply shifts in a more structural framework, estimates from a dynamic stochastic general equilibrium (DSGE) model with stochastic variation in home production technology are compared to those from the VAR. To obtain a VAR identification scheme that is consistent with the DSGE model, we cannot solely rely on ``zero-restrictions''. Instead we indirectly specify a proper prior distribution for impulse responses and variance decompositions and update it through the sample information. Our method provides an alternative to recently proposed identification schemes that rely on inequality restrictions on the direction of impulse responses.

Labor-supply shifts and economic fluctuations

We propose a new VAR identification scheme that distinguishes shifts of and movements along the labor demand schedule to identify labor-supply shocks. According to our VAR analysis of post-war US data, labor-supply shifts account for about 30 percent of the variation in hours and about 15 percent of the output fluctuations at business cycle frequencies. To assess the role of labor-supply shifts in a more structural framework, estimates from a dynamic general equilibrium model with stochastic variation in home production technology are compared to those from the VAR.

Technology Shocks Matter

This paper uses the neoclassical growth model to identify the effects of technological change on the US business cycle. In the model there are two sources of technological change: Neutral, which effects the production of all goods homogeneously, and investment-specific. Investment-specific shocks are the unique source of the secular trend in the real price of investment goods, while shocks to both kinds of technology are the only factors which affect labor productivity in the long run. Consistent with previous empirical work which considers only neutral shocks, the results suggest these shocks account for little, about 6 percent, of the business cycle variation in hours worked. In contrast, investment-specific shocks account for about 48 percent, a new finding which suggests that technology shocks are an important source of the business cycle.

Cyclical Movements in Hours and Effort Under Sticky Wages*

We examine the response of a sticky-wage economy to various real and nominal shocks. In addition to variations in hours, we allow for an endogenous response in worker effort per hour. Despite wages being predetermined, the labor market clears through the effort margin. We find that the ability of a sticky-wage model to mimic U.S. business cycles is much improved by allowing for reasonable effort movements. The model also provides a ready explanation for the finding that TFP is negatively affected by nominal shocks. [E24]

Line-profile variations of the double-lined spectroscopic binary $\mathsf{\kappa}$ Scorpii

We present a total time series of high signal-to-noise, high-resolution spectra of the SiIII 4552:6, 4567: 8a nd4574:8 A lines of the fast-rotating, spectroscopic binary and Cephei star Scorpii. Among this data set is a sample of 422 spectra of intensive monitoring during eight subsequent nights in July 1997. We nd variability of the line proles on two time-scales: a variation of several months as a result of the orbital motion and rapid variations of a few hours, which are explained in terms of non-radial pulsation modes. From the total dataset, covering a time span of 9 years, we derive for the rst time the orbital parameters of Scorpii and nd an orbital period of 195 days. The complex patterns on the grayscale representations of the residual SiIII 4552:6 A proles with respect to the average prole point towards more than one (non-axisymmetric) pulsation mode. A frequency analysis of the three normalised velocity moments conrms the main period of 4.80 hours and the second period of 4.93 hours, which were previously derived from photometric data. We attempt an identication of the pulsation modes by means of the moment method and line-prole tting and nd that Scorpii pulsates in a main prograde sectoral mode of degree 1 or 2 and in an additional tesseral mode for which l =5 ,m =1a re the most likely wavenumbers. In the variations of the line proles we nd indications for the presence of additional pulsation modes.

Women’s Employment Status and Hours Employed in Urban Brazil: Does Husbands’ Presence Matter?

The determinants of hours worked for employed women in developing countries is a little‐studied topic. We compare the determinants of employment with the determinants of hours worked for prime‐aged urban Brazilian women with and without husbands present. Given employment status, we find systematic differences for women in couple‐headed and female‐headed households. For the former, the same variables that affect employment do a good job of explaining hours worked. In contrast, our model generally fails to capture determinants of variation in hours worked for women who are sole heads of households. Sample selectivity functions in opposite directions for the two groups.

Statistical method to evaluate management strategies to decrease variability in operating room utilization: application of linear statistical modeling and Monte Carlo simulation to operating room management.

Operating room (OR) managers seeking to maximize labor productivity in their OR suite may attempt to reduce day-today variability in hours of OR time for which there are staff but for which there are no cases ("underutilized time"). The authors developed a method to analyze data from surgical services information systems to evaluate which management interventions can most effectively decrease variability in underutilized time. The method uses seven summary statistics of daily workload in a surgical suite: daily allocated hours of OR time, estimated hours of elective cases, actual hours of elective cases, estimated hours of add-on cases, actual hours of add-on cases, hours of turnover time, and hours of underutilized time. Simultaneous linear statistical equations (a structural equation model) specify the relationship among these variables. Estimated coefficients are used in Monte Carlo simulations. The authors applied the analysis they developed to two OR suites: a tertiary care hospital's suite and an ambulatory surgery center. At both suites, the most effective strategy to decrease variability in underutilized OR time was to choose optimally the day on which to do each elective case so as to best fill the allocated hours. Eliminating all (1) errors in predicting how long elective or add-on cases would last, (2) variability in turnover or delays between cases, or (3) day-to-day variation in hours of add-on cases would have a small effect. This method can be used for decision support to determine how to decrease variability in underutilized OR time.

Using aspects of predator-prey theory to evaluate helicopter shooting for feral pig control

Because it achieves rapid reductions in pig density, helicopter shooting is perceived to be a cost-effective option for feral pig control. In order to evaluate the cost effectiveness of the technique and develop predictive models of variation in costs, functional response models derived from predator–prey theory were fitted to 3 data-sets describing variation in kill rates with feral pig density. The data-sets were collected during shooting programs conducted on the Mary River floodplain in northern Australia, and on the Macquarie Marshes and Paroo River floodplain in western New South Wales. Fitted models indicated that variation in kill rates with pig density took the form of a Type 3 functional response for all 3 data sets, kill rates approaching a constant maximum at high pig densities and declining toward 0 at pig densities greater than 0. While maximum kill rates were similar for the 3 shooting programs (average 60.49 kill h–1, range 49.64–76.28), densities below which no pigs would theoretically be killed varied significantly (average 2.79 pigs km–2, range 1.34–5.02). Similar maximum kill rates for the 3 shooting programs indicates that, once located, the time taken by shooting teams to dispatch pigs was relatively constant (0.023 h). Variation in threshold densities below which no more pigs would theoretically be shot, indicates that as the density of pigs was reduced, their vulnerability to shooting teams differed between the 3 shooting programs. This may have reflected differences between sites in either the capacity of resident pigs to learn to evade shooting teams or, more likely, the availability of refuge habitat. For 2 of the shooting programs, too few data were available to estimate the effect of declining pig density on kill rate, precluding detailed examination of differences in the efficiency with which pigs were found (search efficiency). Using estimates of pig density below which no pigs would theoretically be shot to set a limit to the effectiveness of shooting programs, models predicting variation in hours per kill with pig density were derived from each data set. These models demonstrated that hours per kill increased exponentially as shooting reduced pig populations below threshold densities of approximately 2–6 pigs km–2. Generalised models relating variation in cost per kill to pig density for the 3 shooting programs are described.

Poaceae pollen in the atmosphere of Santiago de Compostela: its relationship with meteorology

This work analyses the behaviour of Poaceae pollen during a 3-year sampling period (1993–1995) in the city of Santiago de Compostela (Spain). This taxon is shown to be one of the most abundant in the atmosphere, with representation percentages greater than or equal to 20% of total pollen registered during the said period. Its main pollination period is centred on the months of June and July, with slight modifications in the beginning and finalization dates of the years 1993 and 1994 and a significantly earlier beginning in the year 1995. Overall results show that its presence may be considered significant from the end of May to the first days of August. The differences in Poaceae pollen representation are related to variations in temperature, precipitation and hours of sunshine.

New evidence on labor supply:: Employment versus hours elasticities by sex and marital status

Using the tri-annual micro panel data of the Survey of Income and Program Participation we estimate fixed effects labor supply models separating the extensive and intensive margins. The employment elasticity is +0.6 for single men versus +1.1 for married men; the employment elasticity is +2.4 for single women versus +1.8 for married women. The compensated hours worked elasticity is +0.4 for employed single and married men and +0.7 for employed single and married women. The implied aggregate employment elasticity of +1.5 and hours per employee elasticity of +0.5 indicate employment fluctuations account for three-fourths of wage-induced variation in labor hours.

Pireliometria de banda larga e turbidez atmosférica em São Paulo

Este trabalho analisa observacoes de irradiância direcional solar incidente a proximidade do solo sob ceu aberto, em Sao Paulo (SP, Brasil; 23°34'S, 46°44'W, 730 metros de altitude), no intuito de se avaliar a importância do material particulado em suspensao (aerossol) sobre a transparencia da atmosfera no espectro visivel. Esta influencia e discutida em termos da profundidade optica do aerossol, avaliada a partir de dados pireliometricos coletados com filtros de banda larga. Testes de sensibilidade avaliam a importância de algumas fontes de erros sistematicos, como as caracteristicas dos filtros e a calibracao do instrumento. A qualidade de estimativas de profundidade optica aumenta com o proprio nivel de turbidez atmosferica, sendo normalmente baixa (incertezas relativas acima de 100 %) sob condicoes atmosfericas associadas a reduzido conteudo em aerossol. A analise de todo o conjunto de dados coletado entre marco de 1995 a janeiro de 1996 mostra que a profundidade optica do aerossol pode assumir valores muito reduzidos apos a ocorrencia de chuva. Ainda, esta profundidade optica pode exibir variacoes importantes em poucas horas, talvez como consequencia do regime de ventos e do ciclo diurno da umidade relativa do ar. Estudos futuros neste tema devem empregar instrumental mais acurado, instalado num sitio onde ocorram observacoes meteorologicas de rotina.