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

 描述(由申请人提供)： 观察性研究必须依靠计算昂贵的实验后平衡程序，如匹配或倾向分数调整，以解决随机缺失时的无反应偏差。如果缺失的机制是不可忽视的，那么依赖于有效性不确定的建模过程，计算就会变得更加复杂。除了时间密集和成本高昂外，这些方法还必须在数据收集结束后，在没有进一步机会纠正根本偏见的情况下应用。此外，这些方法并不总是产生正确的答案，有时还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，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3X2X2因素、随机、对照试验，以检验两种不同类型的求职信操作的影响，一种在三个水平上，另一个在两个水平上， 以及来自持久自由、伊拉克自由和/或新黎明行动(OEF/OIF/OND)的480名男性和480名女性退伍军人的两种不同的事后付款，他们也在申请退伍军人创伤后应激障碍福利。(2)利用收集到的信息确定招募OEF/OIF/OND退伍军人中偏见最小的小组进行长期评估的最佳方法，描述目标人群的关键特征，并计算用于未来队列研究的力量估计的初步效应量。项目方法：利用退伍军人福利管理数据库，我们将随机抽取480名男性和480名女性(共960名)退伍军人作为性别分层样本，他们正在积极申请创伤后应激障碍残疾福利。退伍军人将收到我们预期在未来队列中使用的相同调查问卷。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的抽样框架。除了性别之外，还将研究5个其他特征，因为受访者/非受访者在这些特征上的差异可能具有信息性(不可忽视)。这些因素是：退伍军人的战斗暴露、军中性创伤暴露、年龄、种族和精神疾病严重程度。调查结束后，我们还将评估退伍军人的 索赔结果(获奖/未获奖)。调查求职信的两个组成部分将有所不同 交叉：首先，调查的内容将以三种方式之一进行描述。其次，退伍军人将被给予两种描述之一，说明他们的名字是如何在研究中获得的。第三，也是最后一项，退伍军人将随机获得一张20美元或40美元的事后礼品卡，以完成调查。我们之前的研究与杠杆-突显理论很好地吻合，表明这些求职信元素和支付水平可能会导致信息性的无回应偏差或不可忽视的单位缺失。这项研究的主要结果是检查每个研究条件下的单位水平失配，并测试缺失的机制是完全随机的，还是在控制其他协变量后随机的，还是不可忽略的。次要结果检查调查项目水平的遗漏，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 还有那封求职信。对于最后一个目标，主要结果是在他们的索赔被决定之前成功招募的退伍军人的比例，从退伍军人提交到收到索赔决定的以天为单位的时间，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%，β=0.80，双尾阿尔法=0.05，该研究被授权识别受访者和父母群体之间的总偏差(偏差的标志)，每个研究条件的总偏差最小为0.13，不同研究条件的总偏差约为0.03。一个小效应(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).