Clinical research associates (CRAs) do not replace investigators, radiologists or central readers and they do not independently perform a medical interpretation of imaging. Nevertheless, they regularly interact with RECIST-derived source data. Their responsibilities include source data review, verification of data entered into the electronic data capture (EDC) system, identification of inconsistencies between imaging reports and case report forms, follow-up of missing assessments and escalation of potential discrepancies to medical or imaging experts. These activities require not simply familiarity with RECIST terminology – they require a practical understanding of how the criteria are applied, or in other words – practical skills rather than theoretical knowledge.