Large-scale surveys that encourage participation through multi-faceted communications campaigns, such as the decennial Census, have typically experienced challenges attributing positive impacts to specific communication efforts (Datta et. Al, NORC 2012). As data collection efforts increasingly move online, the use of tracking codesvia URL hyperlinks can help enhance attribution toidentify what outreach modes were successful at encouraging response, especially among specific populations of interest. This paper explores results from a 2015 Census Test to identify the proximal communication channels that resulted in survey submissions. These channels include both online and traditional offline outreach methods, including digital advertising, partner promotion, postcards, QR codes, and opt-in text messages. By connecting user-provided response information with outreach channel-specific tracking information, the authors provide a more nuanced view of how survey participants engage with the data collection efforts and which response channels are directly effective at boosting participation. Using the URL-based attribution, the authors analyze the performance of digital advertisements to directly increase participation in data collection efforts. Results from three small-scale digital tests are discussed, including use of concrete directions in advertising call-to-actions, the appeal of localized language, and the impact of different legal requirement phrases. These tests emphasize the importance of placement and audience selection in digital advertising and suggest further opportunities for research on applications for survey collection. Implications for security standards in the context of the federal government and participant privacy are also discussed.