This paper increases understanding of the accuracy of consumers' self-reports about using brands and categories. The researchers select television viewing as the category of usage firstly, due to the availability of robust panel data for validation of the claimed data (i.e. self-reported) and secondly, because watching television and purchasing fast moving consumer goods have similar underlying structures in consumer behavior (Ehrenberg, 1969; Goodhardt, Ehrenberg, & Collins, 1975). The results show that light users (viewers) are the main source of error at both brand (program) and category (total television viewing) levels. At brand level, the data shows underestimation of once-only events, which suggests that those who engage in behavior infrequently either forget that the event has occurred, or do not form a representation of the event in memory. At category level, light users tend to generalize their responses to reflect the regularity of the behavior, which manifests in fewer non-users in claimed data. Regardless of the measurement level, the main questioning challenge is getting less frequent users to accurately report an event occurring. The paper provides recommendations for brand researchers on how to minimize the errors caused by responses from light users, which will increase the accuracy of the usage metrics overall. (C) 2012 Elsevier Inc. All rights reserved.