Lee Ji-Hyun, Eschrich Steven, Beam Craig
H. Lee Moffitt Cancer Center Research Institute, University of South Florida, Tampa, FL 33612, USA.
Biom J. 2007 Aug;49(5):672-81. doi: 10.1002/bimj.200610314.
Radiologists' interpretation on screening mammograms is measured by accuracy indices such as sensitivity and specificity. The hypothesis that radiologists' interpretation on screening mammograms is constant across time can be tested by measuring overdispersion. However, small sample sizes are problematic for the accuracy of asymptotic approaches. In this article, we propose an exact conditional distribution for testing overdispersion of the binomial assumption that is assumed for the accuracy indices. An exact p -value can be defined from the developed distribution. We also describe an algorithm for computing this exact test. This proposed method is applied to data from a study in reading screening mammograms in a population of US radiologists (Beam et al., 2003). The exact method is compared analytically with a currently available method based on large sample approximations.
放射科医生对乳腺筛查钼靶的解读通过诸如敏感度和特异度等准确性指标来衡量。放射科医生对乳腺筛查钼靶的解读随时间保持不变这一假设，可以通过测量过度离散来检验。然而，小样本量对于渐近方法的准确性存在问题。在本文中，我们提出一种精确的条件分布，用于检验准确性指标所假定的二项式假设的过度离散。可以从所构建的分布中定义精确的p值。我们还描述了一种计算此精确检验的算法。所提出的方法应用于一项关于美国放射科医生群体阅读乳腺筛查钼靶的研究数据（Beam等人，2003年）。将该精确方法与基于大样本近似的现有方法进行了分析比较。
