Ensuring trial conduct is consistent with trial design: assumption is the enemy of quality

'Assumptions are made and most assumptions are wrong' (Albert Einstein) Clinical trial conduct must be consistent with trial design, yet conducting the trial according to plan remains a major challenge.We discuss the importance of optimal co-applicant team formation in trial leadership, appropriate delegation of tasks and staff supervision arrangements. Finally, we discuss five standard documents which we believe require particular attention. With appropriate engagement by or with co-applicants during the preparation of these five standard documents, we believe many of the pitfalls trials commonly experience can be avoided. The risks inherent in failing to identify and address mistaken assumptions during the preparation of these documents are discussed and recommendations for best practice suggested.