PLease do not answer if you are reading this: respondent attention in online panels

This paper reports on the relevance of attention checks for online panels, e.g., M-Turk, SurveyMonkey, SmartSurvey, QualTrics. In two SmartSurvey studies approximately one third of the respondents failed a check that instructed them to skip the question. Attention-enhancing tools reduce this to approximately one fifth. The failure rate is not affected by replacing multiple-item scales with single-item measures. We find that failing the attention check relates to other attention indicators and that decreased attention levels often apply across the length of the survey. In support of relevance, our empirical findings show respondent inattentiveness systematically biases survey responses.