National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Stat Med. 2011 Feb 28;30(5):505-14. doi: 10.1002/sim.3911. Epub 2011 Feb 4.
Random-digit-dial telephone surveys are experiencing both declining response rates and increasing under-coverage due to the prevalence of households that substitute a wireless telephone for their residential landline telephone. These changes increase the potential for bias in survey estimates and heighten the need for survey researchers to evaluate the sources and magnitudes of potential bias. We apply a Monte Carlo simulation-based approach to assess bias in the NIS, a land-line telephone survey of 19-35 month-old children used to obtain national vaccination coverage estimates. We develop a model describing the survey stages at which component nonsampling error may be introduced due to nonresponse and under-coverage. We use that model and components of error estimated in special studies to quantify the extent to which noncoverage and nonresponse may bias the vaccination coverage estimates obtained from the NIS and present a distribution of the total survey error. Results indicated that the total error followed a normal distribution with mean of 1.72 per cent(95 per cent CI: 1.71, 1.74 per cent) and final adjusted survey weights corrected for this error. Although small, the largest contributor to error in terms of magnitude was nonresponse of immunization providers. The total error was most sensitive to declines in coverage due to cell phone only households. These results indicate that, while response rates and coverage may be declining, total survey error is quite small. Since response rates have historically been used to proxy for total survey error, the finding that these rates do not accurately reflect bias is important for evaluation of survey data. Published in 2011 by John Wiley & Sons, Ltd.
随机数字拨号电话调查由于越来越多的家庭使用无线电话代替住宅固定电话，因此面临着回应率下降和覆盖范围缩小的问题。这些变化增加了调查估计中出现偏差的可能性，并提高了调查研究人员评估潜在偏差的来源和程度的必要性。我们应用基于蒙特卡罗模拟的方法来评估 NIS（针对 19-35 个月大儿童的固定电话调查，用于获取全国疫苗接种覆盖率估计）中的偏差。我们开发了一个模型，描述了由于无回应和覆盖范围缩小可能在调查阶段引入的组件非抽样误差。我们使用该模型和在特殊研究中估计的误差组件来量化非覆盖和无回应可能对从 NIS 获得的疫苗接种覆盖率估计产生的偏差程度，并呈现总调查误差的分布。结果表明，总误差遵循正态分布，均值为 1.72%（95%置信区间：1.71%，1.74%），并对最终调整后的调查权重进行了校正，以纠正这种误差。尽管很小，但从数量上看，误差最大的原因是免疫提供者的无回应。总误差对仅使用手机的家庭导致的覆盖率下降最为敏感。这些结果表明，尽管回应率和覆盖率可能在下降，但总调查误差很小。由于回应率历来被用作总调查误差的代理，因此发现这些率不能准确反映偏差对于评估调查数据非常重要。2011 年由 John Wiley & Sons, Ltd. 出版。
