The Labor Required for Crop Production in Ohio

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An Evaluation of Instrumental Variable Strategies for Estimating the Effects of Catholic Schools

Several previous studies have relied on religious affiliation and the proximity to Catholic schools as exogenous sources of variation for identifying the effect of Catholic schooling on a wide variety of outcomes. Using three separate approaches, we examine the validity of these instrumental variables. We find that none of the candidate instruments is a useful source of identification of the Catholic school effect, at least in currently available data sets

The application of the microgenetic method to studies of learning in science education: characteristics of published studies, methodological issues and recommendations for future research

This paper examines the role of the microgenetic method in science education. The microgenetic method is a technique for exploring the progression of learning in detail through repeated, high-frequency observations of a learner’s ‘performance’ in some activity. Existing microgenetic studies in science education are analysed. This leads to an examination of five significant methodological issues in microgenetic research. Firstly, qualitative and/or quantitative approaches to data collection and analysis within the microgenetic approach are considered and a case is made for the appropriateness of qualitative microgenetic research. Secondly, it is argued that researchers may define static intervals, periods within which (for methodological purposes) change is assumed not to occur, when reporting microgenetic studies. Thirdly, researchers should consider providing justifications for their choice of sampling rate with reference to the rate of change of the phenomenon they are studying. Fourthly, the difficulty of distinguishing conceptual change from the existence of multiple understandings is highlighted. Finally, the nature of sequences of repeated measures in microgenetic studies is considered. It is argued that different methodological approaches are suitable for microgenetic studies of different phenomena and a list of guidelines for the use of the microgenetic method in small-scale, qualitatively analysed studies in science education is proposed

Direct Estimation of Policy Impacts

This paper specifies a general set of conditions under which the impacts of a policy can be identified using data generated under a different policy regime. We show that some of the policy impacts can be identified under relatively weak conditions on the data and structure of a model. Based on the identification results we develop estimators of policy impacts. We discuss a nonparametric method to implement the estimation but also discuss semiparametric methods in order to reduce the conditioning dimension. We then provide an empirical example of the impact of tuition subsidies using the ideas. While the framework used in this paper is fairly narrow, we believe this approach can be applied to a broad set of problems.

Containment Basins And Bird Exclusion-A Historical Perspective

Most facility engineers with responsibility for hazing birds on containment basins use agricultural crop protection techniques. This approach is appropriate for basins with non-hazardous solutions. Basins containing toxic solutions require an entirely different approach. Detoxification, or exclusion with floating membranes, netting or Bird Balls™ are the best options

The spatial distribution of gender differences in obesity prevalence differs from overall obesity prevalence among US adults

While obesity disparities between racial and socioeconomic groups have been well characterized, those based on gender and geography have not been as thoroughly documented. This study describes obesity prevalence by state, gender, and race/ethnicity to (1) characterize obesity gender inequality, (2) determine if the geographic distribution of inequality is spatially clustered and (3) contrast the spatial clustering patterns of obesity gender inequality with overall obesity prevalence