Department of Statistics, Florida State University, Tallahassee, FL 32306, USA.
Community Dent Oral Epidemiol. 2012 Feb;40 Suppl 1(Suppl 1):21-7. doi: 10.1111/j.1600-0528.2011.00662.x.
Calibration studies are routinely performed to establish examiner reliability in clinical periodontal research. In these studies, each periodontal site is assessed in duplicate, enabling point and interval estimation of agreement measures. We show how these data can be used additionally to discover subgroups among the periodontal sites according to degree of agreement with true periodontal status and to identify factors associated with examiner bias.
A Bayesian hierarchical model is developed that, for all examiners, links the examiner's recorded measurement with the site's true periodontal status, allowing for site-specific examiner effects on the recorded measurement. These site-specific examiner effects are modeled as arising from a Dirichlet process mixture, which yields a small number (relative to the number of sites) of distinct effects for each examiner. Hence, sites that share the same examiner effect form a subgroup for which that examiner exhibits consistent bias relative to truth. We fit this model to data from a pilot calibration study for probed pocket depth measurements and use the results to explore examiner-specific groupings of sites according to degree of agreement with true pocket depth. The discovered group assignments were then associated with characteristics of the site.
The Bayesian hierarchical modeling revealed that periodontal sites were grouped according to bias into three, two, and two subgroups, respectively, for each of the three study examiners. The magnitude of the bias was associated with tooth position and true depth of the pocket.
Our Bayesian hierarchical model enhances the utility of data obtained from calibration studies for periodontal pocket depth by facilitating discovery of subgroups of sites according to examiner bias. The results indicate that targeting specific tooth locations and pocket depths during examiner training, uniquely for each examiner, may reduce bias in periodontal pocket depth measurements, thereby enhancing the quality of oral epidemiologic research.
在临床牙周研究中，通常会进行校准研究以确定检查者的可靠性。在这些研究中，每个牙周部位均进行两次评估，从而可以对一致性测量指标进行点估计和区间估计。我们展示了如何另外利用这些数据根据与真实牙周状况的一致性程度来发现牙周部位中的亚组，并确定与检查者偏差相关的因素。
建立了一个贝叶斯层次模型，该模型使所有检查者的记录测量值与部位的真实牙周状况相关联，从而允许检查者对记录测量值产生部位特异性影响。将这些部位特异性检查者效应建模为来自狄利克雷过程混合模型的结果，从而为每个检查者产生相对较少（相对于部位数量）的不同效应。因此，具有相同检查者效应的部位形成一个亚组，该亚组的检查者相对于真实值表现出一致的偏差。我们将该模型拟合到探测袋深度测量的初步校准研究数据中，并使用结果根据与真实袋深度的一致性来探索检查者特异性部位分组。然后，将发现的分组分配与部位的特征相关联。
贝叶斯层次建模揭示了根据偏差将牙周部位分组为三个、两个和两个亚组，分别为三个研究检查者中的每一个。偏差的大小与牙齿位置和口袋的真实深度相关。
我们的贝叶斯层次模型通过促进根据检查者偏差发现部位亚组，增强了从校准研究中获得的数据在牙周袋深度方面的实用性。结果表明，针对每个检查者的特定牙齿位置和口袋深度在检查者培训期间进行针对性培训，可能会减少牙周袋深度测量中的偏差，从而提高口腔流行病学研究的质量。
