构建更好的数据集

凯瑟琳·泽勒（凯瑟琳Zeiler）在乔治梅森大学法律与经济中心的资助下，对医疗事故保险费进行了大规模的实证澳门威尼斯人注册网站研究。

Nancy Barton Scholar and Professor of Law 凯瑟琳Zeiler is no stranger to empirical studies. Zeiler拥有南加州大学法学院的法学博士和加州理工学院的经济学博士学位，经常将经济理论和实证方法应用于法律问题。

As a professor in BU Law’s highly ranked 卫生法专业, Zeiler is interested in how legal rules impact health-related outcomes, like the price of physician services or how many people are able to obtain health insurance. Her current project is an empirical analysis of state statutory tort reforms using her own data, collected with the help of a $105,000 grant from George Mason University’s Law & Economics Center.

医疗事故保险费较高的国家往往会制定法规，限制索赔人可能寻求的损害赔偿金额，目的是稳定医疗事故保险市场。 “The conventional wisdom is that the liability system is out of control,” Zeiler says. “Politicians regularly claim that juries hand down outsized awards and that the liability system is plagued by uncertainty and errors. They point to these factors as the cause of high prices in medical malpractice insurance markets.” 断言并没有就此结束。 泽勒注意到一些澳门威尼斯人注册医生离开市场不稳定的州的说法，这将使医生的供应面临风险。 这种趋势在产科和神经外科领域尤其令人不安，无论保险市场如何要求，这些领域都是高风险和高成本的领域。

“A number of studies have been published that attempt to estimate the impacts of damages caps on medical malpractice insurance premiums to determine if the caps are working in the way state legislatures expect them to,” Zeiler says. In a 2013 review of the existing literature entitled “损害赔偿上限会降低医疗事故保险费吗？：对估算及其产生方法的系统回顾,” published in 2013 in the 侵权经济学澳门威尼斯人注册网站研究手册, Zeiler found that the published research relied on studies with severe limitations. “许多数据集是基于各州收集的总保费，这使得不可能将保险单销售数量的变化与价格的变化分开。 其他数据集包括仅针对一种保单规模的定价，通常是每次承保100万美元，每年承保300万美元的保单。”

Zeiler’s study will join the conversation as the 17th study of the impact of damages caps on medical malpractice premiums. GMU的拨款使她能够建立一个原始数据集，从州文件中收集医疗事故保险定价数据，按县、政策规模、年份、保险公司和提供商类型分列。

一旦收集到这些数据，泽勒和她的合著者、西北大学法学院的迈克尔·弗雷克斯（Michael Frakes）将利用这些数据，采用最先进的经验方法来估计医疗事故保费上限的影响。 泽勒说：“一旦数据集完成，我们将利用它来对医疗事故损害赔偿上限对保险价格的影响做出迄今为止最全面、最准确的估计。”

对经验方法的改进集中在最大限度地减少在现场而不是在受控的实验室环境中澳门威尼斯人注册网站研究数据的影响。 “In a perfect world, we could randomize which states impose damages caps and which don’t,” Zeiler says. “Our inability to do that leads to problems with drawing causal inferences from observed outcomes, like the correlation between insurance prices and tort reform. 我们试图通过这项澳门威尼斯人注册网站研究改进的一件事是控制澳门威尼斯人注册网站研究样本中选择偏差可能性的机制。 Observed spikes in medical malpractice premiums lead us to believe that states that opt to impose caps are not random, as you would want them to be in a lab experiment.”

In her study, Zeiler is using a common statistical estimator called “difference-in-differences,” in which medical malpractice insurance premiums in states that impose caps, the treatment states, are measured at specific times before and after caps are imposed. 在没有设定上限的受控州，保费也在同一时间计算。 “差异中的差异”然后估计了那些没有实施上限的州在接受治疗的州的保费平均变化。 预期溢价变化和观察到的溢价变化之间的差异是Zeiler所追求的差异中的差异。

“This is one method that researchers use to mimic a laboratory experiment using observational field data,” Zeiler says. “An important assumption missed in previous studies is that the control states are actually useful controls. 这需要对照状态的治疗前趋势遵循治疗状态的趋势。 只有当这个假设满足时，我们才能确信控制状态可以帮助我们估计必要的反事实。” 在2013年对现有澳门威尼斯人注册网站研究的回顾中，泽勒指出，没有一项澳门威尼斯人注册网站研究报告了这种检查的结果，这让她对这些澳门威尼斯人注册网站研究的结果以及基于这些澳门威尼斯人注册网站研究的分析提出了质疑。

With data collection ongoing, the timeline for Zeiler and Frakes’s analysis is undetermined, although they hope to begin work-shopping preliminary drafts in spring 2016. 然而，这项澳门威尼斯人注册网站研究的重要性及其影响卫生政策的潜力并没有被Zeiler忽视。 她说：“在国家高度关注卫生保健费用和获取的时候，我们准确估计责任制度的直接和间接影响的能力至关重要。” “更全面的医疗事故保险费数据集和最先进的实证方法的使用，将使我们在更好地理解责任制度的实际影响方面向前迈出一大步。”