As nonresponse rates and costs of traditional data collection modes increase, more people are becoming interested in Web surveys as an alternative. Although there are great concerns about
coverage errors in Web surveys, the simultaneous advantages of Web surveys—timeliness, cost-saving, various design options, and applicability to mixed modes—make them attractive survey modes. This study focuses on response time using paradata and survey responses from the Internet component of the Gallup Panel. Usually, response time is highly skewed. For example, while the average total response time for a Gallup Panel survey in June was 295.15 seconds, the maximum total response time was 4561.24 seconds. To handle outliers with very long response times, Yan and Tourangeau (2008) replaced observations beyond the upper one percentile with the ninety-ninth percentile value and observations below the lower one percentile with the first percentile value, respectively. This study, however, focuses on the outliers themselves, especially those with extremely long response times. Outliers are potentially important because they provide cues to identify respondent behavior and response patterns. In a preliminary analysis, cutting outliers with long response times at certain points excluded nearly one-third of the participants who broke off from the analysis. Also, there were significant differences in the percentages of item nonresponse between outliers and non-outliers. Despite their importance, outliers tend to be excluded from the analysis because of their great leverage to the overall results. Instead of discussing the optimal cutoff points for outliers, this study aims to examine the features of outliers in online panel surveys and suggests that outliers with long response latencies be investigated for researchers to understand respondent behavior and improve data quality. Exploring response time outliers through paradata may show us a novel way to approach various issues concerning Web surveys.