Plausibility checks should include range checks on variables supplied, asking the original investigators to confirm any extreme outliers or unusual values: for example, confirming that records of unusually old or young patients or those with abnormally high or low cholesterol levels are indeed correct. Information supplied should also be checked against any relevant study publications, for example by confirming that the distribution of baseline characteristics, the number of participants and outcome results are consistent (bearing in mind that continued enrolment or additional follow-up may have altered information subsequent to publication).