TY - JOUR AU - Broberg, Per PY - 2013 DA - 2013/07/19 TI - Sample size re-assessment leading to a raised sample size does not inflate type I error rate under mild conditions JO - BMC Medical Research Methodology SP - 94 VL - 13 IS - 1 AB - One major concern with adaptive designs, such as the sample size adjustable designs, has been the fear of inflating the type I error rate. In (Stat Med 23:1023-1038, 2004) it is however proven that when observations follow a normal distribution and the interim result show promise, meaning that the conditional power exceeds 50%, type I error rate is protected. This bound and the distributional assumptions may seem to impose undesirable restrictions on the use of these designs. In (Stat Med 30:3267-3284, 2011) the possibility of going below 50% is explored and a region that permits an increased sample size without inflation is defined in terms of the conditional power at the interim. SN - 1471-2288 UR - https://doi.org/10.1186/1471-2288-13-94 DO - 10.1186/1471-2288-13-94 ID - Broberg2013 ER -