Accuracy of Geographically Targeted Internet Advertisements on Google Adwords for Recruitment in a Randomized Trial
Accuracy of Geographically Targeted Internet Advertisements on Google Adwords for Recruitment in a Randomized Trial
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DOI：
10.2196/jmir.1991
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发表时间：
2012-05-01
影响因子：
7.4
通讯作者：
Boulos, Maged N. Kamel
中科院分区：
文献类型：
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作者：
Jones, Ray B.;Goldsmith, Lesley;Boulos, Maged N. Kamel
背景：Google AdWords 越来越多地用于招募人员参与研究和临床服务。它们提供了在整群随机对照试验 (RCT) 中从目标控制区域招募人员的潜力，但人们对按位置准确定位广告并与控制区域进行比较的可行性知之甚少。目的：在试点集群 RCT 中使用 Google AdWords 进行定位在线干预来检查控制区域的准确性和污染。方法：根据之前使用在线认知行为疗法治疗抑郁症和人口规模，我们有目的地选择了 121 个英国邮政编码区域中的 16 个，并将它们随机分配到三个干预组和一个（无所事事）控制组。两个干预组包括使用针对位置的 AdWords，我们将其与不执行任何操作的对照组进行了比较。我们没有提高我们研究网站在正常网络搜索中的可见度。点击广告的用户会被定向到我们的项目网站，该网站收集计算机互联网协议 (IP) 地址、日期和时间。访客被要求提供他们的邮政编码区域并完成患者健康调查问卷（抑郁症）。然后他们获得了一些在线抑郁症资源的链接。 Google Analytics（分析）主要使用 IP 方法来估计位置，但 AdWords 使用其他信息。我们比较了 (1) Analytics 评估的位置和 (2) 用户自我识别的位置。结果：广告展示了 300,523 次，点击次数为 4207 次。除了通过 AdWord 点击访问之外，网站访问量很少。两种位置评估方法都一致认为控制区域几乎没有受到污染。根据 Analytics 的数据，69.75% (2617/3752) 的参与者位于干预区域，只有 0% (8/3752) 位于对照区域，但 30.04% (1127/3752) 位于其他区域。然而，根据用户提供的邮政编码，只有 20.7% (463/2237) 在干预区，1% (22/2236) 在控制区，但 78.31% (1751/2236) 在其他地区。两次地点评估都表明，干预部门的大部分泄漏都流向了附近的邮政编码区域。分析数据与参与者报告的邮政编码不同。对 10 天内 200/2236 条记录的子集进行分析，将 IP 估计位置与规定的邮政编码进行比较，结果表明 Google AdWords 仅在一半的情况下定位正确。 Analytics（分析）同意我们的评估，即总体而言，三分之一的广告被 AdWords 错误定位。几乎没有证据表明那些愿意提供邮政编码的人没有如实回答。结论：尽管目标区域可能存在大量泄漏，但如果干预区域和控制区域相距足够远，则可以使用在线广告针对英国邮政编码区域进行集群随机对照试验，而不会造成严重污染。
Background: Google AdWords are increasingly used to recruit people into research studies and clinical services. They offer the potential to recruit from targeted control areas in cluster randomized controlled trials (RCTs), but little is known about the feasibility of accurately targeting ads by location and comparing with control areas. Objective: To examine the accuracy and contamination of control areas by a location-targeted online intervention using Google AdWords in a pilot cluster RCT.Methods: Based on previous use of online cognitive behavioral therapy for depression and population size, we purposively selected 16 of the 121 British postcode areas and randomized them to three intervention and one (do-nothing) control arms. Two intervention arms included use of location-targeted AdWords, and we compared these with the do-nothing control arm. We did not raise the visibility of our research website to normal Web searches. Users who clicked on the ad were directed to our project website, which collected the computer Internet protocol (IP) address, date, and time. Visitors were asked for their postcode area and to complete the Patient Health Questionnaire (depression). They were then offered links to several online depression resources. Google Analytics largely uses IP methods to estimate location, but AdWords uses additional information. We compared locations assessed by (1) Analytics, and (2) as self-identified by users.Results: Ads were shown 300,523 times with 4207 click-throughs. There were few site visits except through AdWord click-throughs. Both methods of location assessment agreed there was little contamination of control areas. According to Analytics, 69.75% (2617/3752) of participants were in intervention areas, only 0% (8/3752) in control areas, but 30.04% (1127/3752) in other areas. However, according to user-stated postcodes, only 20.7% (463/2237) were in intervention areas, 1% (22/2236) in control areas, but 78.31% (1751/2236) in other areas. Both location assessments suggested most leakage from the intervention arms was to nearby postcode areas. Analytics data differed from postcodes reported by participants. Analysis of a subset of 200/2236 records over 10 days comparing IP-estimated location with stated postcode suggested that Google AdWords targeted correctly in just half the cases. Analytics agreed with our assessment that, overall, one-third were wrongly targeted by AdWords. There appeared little evidence that people who bothered to give their postcode did not answer truthfully.Conclusions: Although there is likely to be substantial leakage from the targeted areas, if intervention and control areas are a sufficient distance apart, it is feasible to conduct a cluster RCT using online ads to target British postcode areas without significant contamination.