Measuring the impact of online health campaigns is challenging. Traditionally, advertisement click-through rates (CTRs) have been used to measure message reach, but CTRs are low with most clicks coming from a small fraction of users. However, low CTRs do not necessarily indicate that an ad was not effective. There may be latency effects whereby people do not click on ads at time of exposure but visit the promoted website or conduct searches later. Online panels that unobtrusively collect panelists’ web behavior may provide a more reliable data source for measuring online campaign effects. We used web behavior data from a proprietary online panel to identify panelists who were either exposed or unexposed to the Tobacco Free Florida Cessation Internet ad campaign. We assessed whether ad exposure influenced website visits and searches on campaign-related topics up to 4 weeks after initial exposure. Those who were exposed to the campaign were significantly more likely than those who were not exposed to have visited the campaign website (0.65% vs. 0.13%, respectively, p < .001), but ad exposure did not influence searches on campaign-related topics. These results suggest that panel web behavior data may be useful for understanding behavioral response to and latency effects of online campaigns.
