553 research outputs found

    The Effect of School Class Size on Post-Compulsory Education: Some Cost Benefit Analysis

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    This paper is concerned with the relationship between class size and the student outcome – length of time in post-compulsory schooling. Research on this topic has been problematic partly because omitted unobservables, like parents’ incomes and education levels, are likely to be correlated with class size. Two potential ways to resolve this problem are to exploit either experimental or instrumental variation. In both cases, the methods require that the variation in both class size and the outcome should not be contaminated by other unobservable factors that affect the outcome – like family background. An alternative approach, which we pursue here, is to take advantage of variation in class size between siblings which allows unobservable family effects to be differenced out. Our aim is to combine sibling differences with a fuzzy rule that determines class size to provide estimates of the effect of class size and use these to conduct an evaluation of the costs and benefits of a reduction in class sizes.class size, regression discontinuity, sibling differences

    Factors associated with usage of antimicrobials in commercial mink (Neovison vison) production in Denmark

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    AbstractThe American mink (Neovison vison) is used for commercial fur production in Denmark. In recent years, antimicrobial prescription for Danish mink has been increasing. In this study, the patterns and trends in antimicrobial use in mink were described and a multi-variable variance analysis was carried out with the objective of identifying risk factors for antimicrobial use on herd level. The study was based on register data for 2007–2012. Information on antimicrobial use was obtained from the national database VetStat, monitoring all medicinal products used for animals on prescription level. Data on microbiological feed quality was obtained from the Voluntary Feed Control under the Mink producers Organization, and data on herd size and the relation between farm and feed producer was obtained from the registers at Kopenhagen Fur, based on yearly reporting from the mink producers. Descriptive analysis showed a clear significant effect of season on antimicrobial use, with a peak in “treatment proportions”, TP (defined daily doses per kg biomass-days) in May, around the time of whelping, and a high level in the following months. In autumn, a minor peak in antimicrobial use occurred throughout the study period. From 2007 to 2011, a 102% increase in annual antimicrobial TP was noted; on herd level, the increase was associated with an increasing frequency of prescription, and a decrease in the amounts prescribed in months with prescription. A binomial model showed that on herd level, the annual number of months with antimicrobial prescription was significantly (p<0.01) affected by feed producer, veterinarian, disease (specific laboratory diagnosis) infection, herd size and year, with an interaction between feed producer and year. A log-normal model showed that in months with antimicrobial use, the TP on herd level was significantly (p<0.001) affected by year, month (season), feed producer, feed quality score, veterinarian, herd size and laboratory confirmed diagnosis of specific infections; additionally the interaction terms year×feed producer and herd size×month were significant (p<0.001).In conclusion, antimicrobial use on herd level was significantly associated with the microbiological food quality, the feed producer, and the veterinarian. The prescription patterns varied significantly between veterinarians, and some veterinarians were associated with both larger and more frequent prescriptions of antimicrobials at herd level. Herd size is associated with different prescription patterns. Finally, infection with Pseudomonas aeruginosa, astrovirus, influenza virus and Salmonella spp. was associated with an increase in antimicrobial use
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