74 research outputs found

    Whoa, Nellie! Empirical Tests of College Football's Conventional Wisdom

    Get PDF
    College football fans, coaches, and observers have adopted a set of beliefs about how college football poll voters behave. I document three pieces of conventional wisdom in college football regarding the timing of wins and losses, the value of playing strong opponents, and the value of winning by wide margins. Using a unique data set with 25 years of AP poll results, I test college football's conventional wisdom. In particular, I test (1) whether it is better to lose early or late in the season, (2) whether teams benefit from playing stronger opponents, and (3) whether teams are rewarded for winning by large margins. Contrary to conventional wisdom, I find that (1) it is better to lose later in the season than earlier, (2) AP voters do not pay attention to the strength of a defeated opponent, and (3) the benefit of winning by a large margin is negligible. I conclude by noting how these results inform debates about a potential playoff in college football.

    On the Heterogeneity of Dowry Motives

    Get PDF
    Dowries have been modeled as pre-mortem bequests to daughters or as groom-prices paid to in-laws. These two classes of models yield mutually exclusive predictions, but empirical tests of these predictions have been mixed. We argue that the heterogeneity of findings can be explained by a heterogeneous world--some households use dowries as a bequest and others use dowries as a price. We estimate a model with heterogeneous dowry motives and use the predictions from the competing theories in an exogenous switching regression to place households in the price or bequest regime. Our empirical strategy generates multiple, independent checks on the validity of regime assignment. Using retrospective marriage data from rural Bangladesh, we find robust evidence of heterogeneity in dowry motives in the population; that bequest dowries have declined in prevalence and amount over time; and that bequest households are better off compared to price households on a variety of welfare measures.

    Factor Endowments and the Returns to Skill: New Evidence from the American Past

    Get PDF
    The existing literature on skill-biased technical change has not considered how the technological endowment itself plays a role in the returns to skill. This paper constructs a simple model of skill biased technical change which highlights the role that resource endowments play in the returns to education. The model predicts variation in returns to education with skill biased technological change if there is significant heterogeneity in resource endowments before the technological change. Using a variety of historical sources, we document the heterogeneous technology levels by region in the American past. We then estimate the returns to education of high school teachers in the early twentieth century using a new data source. a report from the U.S. Commissioner of Education in 1909. Overall, we find significant regional variation in the returns to education that match differences in resource endowments, with large (within-occupation) returns for the Midwest and Southwest (7%), but much lower returns in the South (3%) and West (0.5%). We also show that our results are generalizable to returns to education in the United States and that returns to education for teachers tracked quite closely with the overall returns to education from 1940 onward.

    Are Engel Curve Estimates of CPI Bias Biased?

    Get PDF
    A recent literature has advanced the use of Engel curves to estimate overall CPI bias. In this paper, I show that the methodology is sensitive to the modeling of household demography. Existing estimates of CPI bias do not account for the changing effect of household size on budget shares, and this can lead to omitted variable bias. Since the effect of household size on demand changes over time the drift in Engel curves attributed to CPI bias is partially explained by this effect. My estimates of the annual rate of CPI bias from 1888 to 1935 are changed by at least 25%, and usually more than 50%, once the changing effect of household size is accounted for.

    Economies of Scale in the Household: Puzzles and Patterns from the American Past

    Get PDF
    Household economies of scale arise when households with multiple members share public goods, making larger households better off at lower per capita expenditures. While estimates of household economies of scale are critical for measuring income and living standards, we do not know how these scale economies change over time. I use American household expenditure surveys to produce the first comparable historical estimates of household scale economies. I find that scale economies changed significantly from 1888 to 1935 for all expenditure categories considered (food, clothing, entertainment, and housing), but not all trends in scale economies are consistent with theoretical predictions. I use these historical estimates of household scale economies to resolve several theoretical and empirical puzzles in the literature. I find that existing explanations for puzzles in the household economies of scale literature do not hold in the past. As such, our notions about household economies of scale must be reassessed in light of this historical evidence.

    The National Rise in Residential Segregation

    Get PDF
    Exploiting complete census manuscript files, we derive a new segregation measure using the racial similarity of next-door neighbors. The fineness of our measure reveals new facts not captured by traditional segregation indices. First, segregation doubled nationally from 1880 to 1940. Second, contrary to prior estimates, Southern urban areas were the most segregated in the country and remained so over time. Third, increasing segregation in the twentieth century was not strictly driven by urbanization, black migration, or white flight: it resulted from increasing racial sorting at the household level. In all areas-North and South, urban and rural-segregation increased dramatically

    Automatic wide complex tachycardia differentiation using mathematically synthesized vectorcardiogram signals

    Get PDF
    BACKGROUND: Automated wide complex tachycardia (WCT) differentiation into ventricular tachycardia (VT) and supraventricular wide complex tachycardia (SWCT) may be accomplished using novel calculations that quantify the extent of mean electrical vector changes between the WCT and baseline electrocardiogram (ECG). At present, it is unknown whether quantifying mean electrical vector changes within three orthogonal vectorcardiogram (VCG) leads (X, Y, and Z leads) can improve automated VT and SWCT classification. METHODS: A derivation cohort of paired WCT and baseline ECGs was used to derive five logistic regression models: (i) one novel WCT differentiation model (i.e., VCG Model), (ii) three previously developed WCT differentiation models (i.e., WCT Formula, VT Prediction Model, and WCT Formula II), and (iii) one all-inclusive model (i.e., Hybrid Model). A separate validation cohort of paired WCT and baseline ECGs was used to trial and compare each model\u27s performance. RESULTS: The VCG Model, composed of WCT QRS duration, baseline QRS duration, absolute change in QRS duration, X-lead QRS amplitude change, Y-lead QRS amplitude change, and Z-lead QRS amplitude change, demonstrated effective WCT differentiation (area under the curve [AUC] 0.94) for the derivation cohort. For the validation cohort, the diagnostic performance of the VCG Model (AUC 0.94) was similar to that achieved by the WCT Formula (AUC 0.95), VT Prediction Model (AUC 0.91), WCT Formula II (AUC 0.94), and Hybrid Model (AUC 0.95). CONCLUSION: Custom calculations derived from mathematically synthesized VCG signals may be used to formulate an effective means to differentiate WCTs automatically

    Using Remote Sensing to Map the Risk of Human Monkeypox Virus in the Congo Basin

    Get PDF
    Although the incidence of human monkeypox has greatly increased in Central Africa over the last decade, resources for surveillance remain extremely limited. We conducted a geospatial analysis using existing data to better inform future surveillance efforts. Using active surveillance data collected between 2005 and 2007, we identified locations in Sankuru district, Democratic Republic of Congo (DRC) where there have been one or more cases of human monkeypox. To assess what taxa constitute the main reservoirs of monkeypox, we tested whether human cases were associated with (i) rope squirrels (Funisciurus sp.), which were implicated in monkeypox outbreaks elsewhere in the DRC in the 1980s, or (ii) terrestrial rodents in the genera Cricetomys and Graphiurus, which are believed to be monkeypox reservoirs in West Africa. Results suggest that the best predictors of human monkeypox cases are proximity to dense forests and associated habitat preferred by rope squirrels. The risk of contracting monkeypox is significantly greater near sites predicted to be habitable for squirrels (OR = 1.32; 95% CI 1.08–1.63). We recommend that semi-deciduous rainforests with oil-palm, the rope squirrel’s main food source, be prioritized for monitoring

    Post-acute COVID-19 syndrome after reinfection and vaccine breakthrough by the SARS-CoV-2 Gamma variant in Brazil.

    Get PDF
    We describe a case of prolonged COVID-19 caused by the SARS-CoV-2 Gamma variant in a fully vaccinated healthcare worker, 387 days after an infection caused by lineage B.1.1.33. Infections were confirmed by whole-genome sequencing and corroborated by the detection of neutralizing antibodies in convalescent serum samples. Considering the permanent exposure of this healthcare worker to SARS-CoV-2, the waning immunity after the first infection, the low efficacy of the inactivated vaccine at preventing COVID-19, the immune escape of the Gamma variant (VOC), and the burden of post-COVID syndrome, this individual would have benefited from an additional dose of a heterologous vaccine

    Metapopulation Dynamics Enable Persistence of Influenza A, Including A/H5N1, in Poultry

    Get PDF
    Thanks to K. Sturm-Ramirez, C. Jessup, J. Rosenthal and the staff of EcoHealth Alliance for feedback. Disclaimer: The contents are the responsibility of the authors and do not necessarily reflect the views of USAID or the United States Government.Conceived and designed the experiments: PRH TF RH DZ CSA AG MJM XX TB PD. Performed the experiments: PRH. Analyzed the data: PRH. Contributed reagents/materials/analysis tools: PRH TF RH DZ CSA AG MJM XX TB JHJ PD. Wrote the paper: PRH TF RH DZ CSA AG MJM XX TB JHJ PD.Highly pathogenic influenza A/H5N1 has persistently but sporadically caused human illness and death since 1997. Yet it is still unclear how this pathogen is able to persist globally. While wild birds seem to be a genetic reservoir for influenza A, they do not seem to be the main source of human illness. Here, we highlight the role that domestic poultry may play in maintaining A/H5N1 globally, using theoretical models of spatial population structure in poultry populations. We find that a metapopulation of moderately sized poultry flocks can sustain the pathogen in a finite poultry population for over two years. Our results suggest that it is possible that moderately intensive backyard farms could sustain the pathogen indefinitely in real systems. This fits a pattern that has been observed from many empirical systems. Rather than just employing standard culling procedures to control the disease, our model suggests ways that poultry production systems may be modified.Yeshttp://www.plosone.org/static/editorial#pee
    • 

    corecore