Home computers and educational outcomes Fairlie, Robert W; Beltran, Daniel O; Das, Kuntal K
Economic inquiry,
July 2010, Letnik:
48, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Although computers are universal in the classroom, nearly 20 million children in the United States do not have computers in their homes. Surprisingly, only a few previous studies explore the role of ...home computers in the educational process. Home computers might be very useful for completing school assignments, but they might also represent a distraction for teenagers. We use several identification strategies and panel data from the two main U.S. data sets that include recent information on computer ownership among children—the 2000–2003 Current Population Survey (CPS) Computer and Internet Use Supplements matched to the CPS basic monthly files and the National Longitudinal Survey of Youth 1997 (NLSY97)—to explore the causal relationship between computer ownership and high school graduation and other educational outcomes. Teenagers who have access to home computers are 6–8 percentage points more likely to graduate from high school than teenagers who do not have home computers after controlling for individual, parental, and family characteristics. We generally find evidence of positive relationships between home computers and educational outcomes using several identification strategies, including controlling for typically unobservable home environment and extracurricular activities in the NLSY97, fixed effects models, instrumental variables, and including future computer ownership and falsification tests. Home computers may increase high school graduation by reducing nonproductive activities, such as truancy and crime, among children in addition to making it easier to complete school assignments (JEL I2).
Studies aimed at identifying BMI cutoffs representing increased diseased risk for Asians are typically based on cross-sectional studies. This study determines an optimal BMI cutoff for overweight ...that represents elevated incidence of hypertension in Chinese adults with data from the China Health and Nutrition Survey 2000-2004 prospective cohort. Cumulative incidence was calculated by dividing new cases of hypertension over the study period by the total at-risk population, aged 18-65 y, in 2000. Sex-specific receiver operating characteristic curves were used to assess the sensitivity and specificity of BMI as a predictor of hypertension incidence. Four-year cumulative incidences of hypertension (13% for women and 19% for men) were related (P < 0.005) to the increase in BMI. The crude area under the curves (AUC) were 0.62 (95% CI: 0.59-0.65) and 0.62 (95% CI: 0.58-0.65) for men and women, respectively; the age-adjusted AUC were 0.68 (95% CI: 0.65-0.70) and 0.71 (95% CI: 0.68-0.74) for men and women, respectively. A BMI of 23.5 kg/m² for women and 22.5 kg/m² for men provided the highest sensitivity and specificity (60%). The finding was consistent in different age groups. A BMI level of 25 kg/m² provided lower sensitivities (36% for women and 29% for men) with higher specificities (80% for women and 85% for men). Our study supported the hypothesis that the BMI cutoff to define overweight should be lower in Chinese than that in Western populations.
Tillage and cropping sequence may influence C and N sequestration, microbial activities, and N mineralization in dryland soil aggregates. We evaluated the 21‐yr effect of tillage and cropping ...sequence combinations on C and N fractions in aggregates of a Dooley sandy loam (fine‐loamy, mixed, superactive, frigid Typic Argiustolls) at the 0‐ to 20‐cm depth in eastern Montana. Tillage and cropping sequences were no‐tilled continuous spring wheat (NTCW) (Triticum aestivum L.), spring‐tilled continuous spring wheat (STCW), fall‐ and spring‐tilled continuous spring wheat (FSTCW), fall‐ and spring‐tilled spring wheat‐barley (Hordeum vulgare L.) (1984–1999) followed by spring wheat‐pea (Pisum sativum L.)(2000–2004)(FSTW‐B/P), and spring‐tilled spring wheat‐fallow (STW‐F). Carbon and N fractions were soil organic C (SOC), total N (STN), particulate organic C and N (POC and PON), microbial biomass C and N (MBC and MBN), potential C and N mineralization (PCM and PNM), NH4–N, and NO3–N. Aggregate proportion was greater in NTCW than in FSTCW in the 4.75‐ to 2.00‐mm aggregate‐size class at 0 to 5 cm but was greater in STW‐F than in STCW in the 2.00‐ to 0.25‐mm size class at 5 to 20 cm. After 21 yr, STW‐F reduced SOC, STN, POC, and PON concentrations in aggregates by 34 to 42% at 0‐ to 5‐cm and by 20 to 32% at 5‐ to 20‐cm compared with NTCW and STCW. The PCM and MBC were greater in NTCW and STCW than in STW‐F in the <2.00‐mm size class at 0 to 5 cm but MBN varied with treatments, aggregate‐size classes, and soil depths. Compared with other treatments, NH4–N concentration was lower in STW‐F in the 4.75‐ to 0.25‐mm size class but PNM and NO3–N were greater in FSTW‐B/P in the <2.00‐mm size class. Long‐term reduced tillage with continuous spring wheat increased soil aggregation, C and N sequestration, and microbial biomass and activities in all aggregates but increased tillage intensity with spring wheat‐barley/pea rotation increased N mineralization and availability in small aggregates compared with the conventional STW‐F.
By investigating differences in social networks among entrepreneurs in 20 cultures, this paper contributes to the debate on whether there is universality in the process of entrepreneurial networking. ...Representative samples of entrepreneurs were identified in the same manner in 20 countries from 2000 to 2004 (
N
= 304,560). The sampling methodologies and the questions asked were similar across all countries. Logistic regression was used to test for significant regional interaction effects involving
personally knowing an entrepreneur
. Results are contrary to the existence of any mono-dimensional form of networking practice but do strongly support the existence of both
variform universality
(culture moderates the importance of networking) and
functional universality
(cultural similarities in networking practice exist).
The research question addressed by this paper is a simple one: are European consumers happy with the price they pay for electricity supply services after two decades of reforms? We focus on ...self-assessed consumers' satisfaction as reported in three waves of the Eurobarometer surveys, 2000–2002–2004, conditioning on a set of indicators of public ownership and liberalisation across the EU-15. After controlling for individual and country characteristics, we find that consumers are happier with the prices they pay when in their country there are both public ownership and liberalisation. We discuss this finding.
Technical efficiency of French retailers Perrigot, Rozenn; Barros, Carlos Pestana
Journal of retailing and consumer services,
07/2008, Letnik:
15, Številka:
4
Journal Article
Recenzirano
This paper analyses the technical efficiency of a sample of French generalist retailers by a two-step procedure. In the first step, four data envelopment analysis (DEA) models are used to identify ...the efficiency scores. This allows the ranking of the retailers to be compiled on the basis of the inputs that they use and the outputs that they produce. In the second step, a Tobit model is bootstrapped in order to identify the drivers of efficiency. Implications of the study are discussed.
Workplace sexual harassment is illegal, but many workers report that they have been sexually harassed. Exposure to the risk of sexual harassment may decrease productivity, which would reduce wages. ...Alternatively, workers may receive a compensating differential for exposure to sexual harassment, which would increase wages. Data on claims of sexual harassment filed with the Equal Employment Opportunity Commission are used to calculate the first measures of sexual harassment risks by industry, age group, and sex. Female workers face far higher sexual harassment risks. On balance, workers receive a compensating wage differential for exposure to the risk of sexual harassment. PUBLICATION ABSTRACT
This article investigates whether the passage and the implementation of the Sarbanes-Oxley Act of 2002 (SOX) drove firms out of the public capital market. To control for other factors affecting exit ...decisions, we examine the post-SOX change in the propensity of American public targets to be bought by private acquirers rather than public ones with the corresponding change for foreign public targets, which were outside the purview of SOX. Our findings are consistent with the hypothesis that SOX induced small firms to exit the public capital market during the year following its enactment. In contrast, SOX appears to have had little effect on the going-private propensities of larger firms. (JEL G30, G34, G38, K22)
An economic analysis of identity and career choice Knoth Humlum, Maria; Kleinjans, Kristin J; Skyt Nielsen, Helena
Economic inquiry,
2012, 2012-01, January 2012, 2012-01-00, 20120101, Letnik:
50, Številka:
1
Journal Article
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Standard economic models tend to be more specific about pecuniary payoffs than nonpecuniary payoffs to education. Based on the ideas of Akerlof and Kranton, we consider a model of career choice and ...identity where individuals derive nonpecuniary identity payoffs. Using factor analysis on a range of attitude questions, we find two factors related to identity (career orientation and social orientation), which are important for planned educational choices and for observed gender differences. The implication is that policy makers and institutions of higher education need to focus on identity‐related issues rather than just improved financial incentives if they aim at attracting high‐ability youths to certain careers. (JEL I21, J24)
We use plant-level data to study the link between the local availability of services and the decision of manufacturing firms to source materials from abroad. We develop a model to generate ...predictions about how the intensity of international sourcing of materials depends on the availability of services and firm characteristics. These predictions are supported by the data. Greater availability of services across regions, industries, and time increases firms' foreign sourcing of materials relative to sales. The impact of services differs by firm type. National firms' sourcing responds to changes in regional service conditions, whereas multinationals tend to be less affected. A l'aide de données au niveau des établissements, on étudie le lien entre la disponibilité locale de services et la décision des entreprises manufacturières de s'approvisionner en biens à l'étranger. On développe un modèle pour engendrer des prédictions quant à savoir jusqu'à quel point l'intensité de l'approvisionnement en biens à l'étranger dépend de la disponibilité des services et des caractéristiques de l'entreprise. Ces prédictions sont supportées par les données. Une plus grande disponibilité de services à travers les régions, les industries et le temps accroît l'approvisionnement en biens à l'étranger des entreprises en pourcentage des ventes. L'impact des services diffère selon le type de firme. L'approvisionnement à l'étranger des entreprises domestiques répond aux variations régionales dans les conditions de service, alors que les entreprises plurinationales tendent à être moins affectées.
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