Cooper, C. ., Whitehead, A. ., Pottrill, E. ., Julious, S. ., & Walters, S. . (2018). Are pilot trials useful for predicting randomisation and attrition rates in definitive studies: A review of publicly funded trials. Clinical Trials (London, England), 1740774517752113. https://doi.org/10.1177/1740774517752113 (Original work published 2018)