Biased Survey-Based Recruiting in Longitudinal Studies: Extent and Remedies

 描述（由申请人提供）： 观察性研究必须依赖于计算昂贵的实验后平衡程序，如匹配或倾向评分调整，以解决随机缺失时的无应答偏倚。如果缺失的机制是不可验证的，那么计算变得更加复杂，依赖于不确定有效性的建模过程。这些方法不仅费时费钱，而且必须在数据收集结束后，即没有机会纠正潜在的偏见时才能使用。此外，这些方法并不总是产生正确的答案，有时会在结果中引入自己的偏见。我们的目标是测试三种方法，如果成功的话，将避免或至少减少设计阶段的无响应偏差。 项目目标：（1）进行一项3X 2X2析因、随机、对照试验，以检查两种不同类型的求职信操作的影响，一种在3个水平，一种在2个水平， 和两种不同的事后付款对无反应偏见的480名男性和480名女性退伍军人从持久自由行动，伊拉克自由，和/或新的黎明（OEF/OIF/OND）谁也申请VA创伤后应激障碍残疾福利。(2)使用收集到的信息确定最佳方法，以招募偏倚最小的OEF/OIF/OND退伍军人小组进行长期评价，描述目标人群的关键特征，并计算未来队列研究把握度估计的初步效应量。项目方法：使用退伍军人福利管理数据库，我们将随机选择480名男性和480名女性OEF/OIF/OND退伍军人（共960名）的性别分层样本，他们正在积极申请PTSD残疾福利。退伍军人将被邮寄相同的调查，我们预计在我们未来的队列使用。在调查之前，我们将为这960名退伍军人创建一个丰富的已知特征抽样框架。除性别外，还将研究其他5个特征，因为这些特征的应答者/非应答者差异可能提供信息（不可验证）。这些因素是：退伍军人的战斗暴露，暴露于军事性创伤，年龄，种族和精神疾病的严重程度。调查结束后，我们还将评估退伍军人的 索赔结果（裁定/未裁定）。调查的求职信的两个组成部分将有所不同， 交叉：首先，调查的内容将被描述在三种方式之一。第二，退伍军人将得到两个描述他们的名字是如何获得的研究之一。第三，也是最后一点，退伍军人将被随机分配到20美元或40美元的事后礼品卡，以完成调查。我们之前的研究，这与杠杆突出理论，表明这些求职信元素和支付水平可能会导致信息的无响应偏差或不可验证的单位缺失。该研究的主要结果检查了每个研究条件下的单位水平缺失，并测试了缺失机制是否完全随机，在控制其他协变量后是否随机，或是否不可验证。次要结果检查了调查项目水平的缺失，调查前后参与者悲伤和紧张程度的变化，参与者对求职信的印象以及参与者的满意度 还有求职信对于最后一个目标，主要结果是在决定索赔之前成功招募的退伍军人的比例，从退伍军人申请到收到索赔决定的天数，以及目标1确定的最小偏差方法的调查响应率。假设总体调查响应率为50%，beta = 0.80，双尾alpha = 0.05，该研究有把握确定受访者与父母人群之间的汇总总偏差（偏倚标记）每种研究条件下小至0.13，研究条件间的总偏差差异汇总约为0.03，一个小的影响（如科恩的d = 0.25）。

 DESCRIPTION (provided by applicant): Observational studies have to rely on computationally expensive, post-experimental balancing procedures, such as matching or propensity score adjustment, to address non-response bias when missingness is at random. If the missing mechanism is non-ignorable, then computations become even more complex, relying on modeling procedures of uncertain validity. Additional to being time-intensive and costly, these methods must be applied after data collection ends, when there is no further opportunity to rectify the underlying bias. Furthermore, these methods do not always yield the correct answer and sometimes introduce their own bias into the results. Our goal is to test three methods that, if successful, would avert or at least reduce non-response bias at the design stage. Project Objectives: (1) To conduct a 3X2X2 factorial, randomized, controlled trial to examine the impact of two different types of cover letter manipulations, one at 3 levels and one at two levels, and two different after the-fact payments on non-response bias in 480 male and 480 female Veterans from Operations Enduring Freedom, Iraqi Freedom, and/or New Dawn (OEF/OIF/OND) who are also applying for VA PTSD disability benefits. (2) To use the information gleaned to identify the best method to recruit the least biased panel of OEF/OIF/OND Veterans possible for long-term evaluation, to describe key characteristics of the targeted population, and to calculate preliminary effect sizes for power estimations for a future cohort study. Project Methods: Using Veterans Benefits Administration databases, we will randomly select a gender stratified sample of 480 male and 480 female OEF/OIF/OND Veterans (960 total) who are actively applying for PTSD disability benefits. Veterans will be mailed the same survey we anticipate using in our future cohort. Prior to survey we will create a rich sampling frame of known characteristics for these 960 Veterans. Besides gender, 5 other characteristics will be studied because respondent/non-respondent differences on these characteristics are likely to be informative (non-ignorable). These are: Veterans' combat exposure, exposure to military sexual trauma, age, race, and psychiatric illness severity. Post-survey, we will also assess Veterans' claim outcome (awarded/not awarded). Two components of the survey's cover letter will be varied and crossed: First, the survey's content will be described in one of three ways. Second, Veterans will be given one of two descriptions of how their name was obtained for the study. Third and last, Veterans will be randomized to receive either a $20 or $40 after-the-fact gift card for completing the survey. Our prior research, which meshes well with Leverage-Salience Theory, suggests that these cover letter elements and payment levels may induce informative non-response bias or non-ignorable unit missingness. The study's main outcome examines unit-level missingness across each study condition and tests whether the missing mechanism is completely at random, random after controlling for other covariates, or non-ignorable. Secondary outcomes examine missingness at the item level of the survey, changes in participants' sadness and tenseness pre- and post-survey, participants' impressions of the cover letter, and participants' satisfaction with the cover letter. For the last objective, the main outcomes are proportion of Veterans successfully recruited before their claim is decided, the time in days from Veterans' filing to receiving a claim decision, and survey response rate for the least biased method identified by Objective 1. Assuming an overall survey response rate of 50%, beta = 0.80, and two-tailed alpha = 0.05, the study is powered to identify a summary total deviation between respondents and the parent population (a marker of bias) as small as 0.13 per study condition and a difference in summary total deviations across study conditions of approximately 0.03, a small effect (such that Cohen's d = 0.25).