ABSTRACT
OBJECTIVE@#To compare different methods for calculating sample size based on confidence interval estimation for a single proportion with different event incidences and precisions.@*METHODS@#We compared 7 methods, namely Wald, AgrestiCoull add z2, Agresti-Coull add 4, Wilson Score, Clopper-Pearson, Mid-p, and Jefferys, for confidence interval estimation for a single proportion. The sample size was calculated using the search method with different parameter settings (proportion of specified events and half width of the confidence interval [ω=0.05, 0.1]). With Monte Carlo simulation, the estimated sample size was used to simulate and compare the width of the confidence interval, the coverage of the confidence interval and the ratio of the noncoverage probability.@*RESULTS@#For a high accuracy requirement (ω =0.05), the Mid-p method and Clopper Pearson method performed better when the incidence of events was low (P < 0.15). In other settings, the performance of the 7 methods did not differ significantly except for a poor symmetry of the Wald method. In the setting of ω=0.1 with a very low p (0.01-0.05), failure of iteration occurred with nearly all the methods except for the Clopper-Pearson method.@*CONCLUSION@#Different sample size determination methods based on confidence interval estimation should be selected for single proportions with different parameter settings.
Subject(s)
Confidence Intervals , Sample Size , Computer Simulation , Monte Carlo Method , ProbabilityABSTRACT
The appropriate sample size estimation is very important in the design of clinical trials. However, insufficient or inappropriate sample size estimation is still a prominent problem in the currently published acupuncture and moxibustion clinical trials. At present, the superiority test, non-inferiority test and equivalence test have been widely used in acupuncture and moxibustion clinical trials. This article focuses on the application, calculation methods and PASS11 software using of these three hypothesis test types. In view of the problems in the estimation of sample size in acupuncture and moxibustion clinical trials, the particularity of sample size estimation in acupuncture and moxibustion is summarized from the aspects of parameter setting, ratio of intervention group and control group, and multi-group comparison, in order to guide acupuncture clinical researchers to correctly estimate sample size when conducting clinical trials.
Subject(s)
Acupuncture , Acupuncture Therapy , Clinical Trials as Topic , Moxibustion , Sample SizeABSTRACT
Objective To propose a method to calculate sample size for survival analysis in single-arm trials.Methods Through theoretical formula derivation,we provided sample size estimation method for survival analysis in single-arm trials.Monte-Carlo simulations using STATA software were conducted to obtain the empirical power,so as to verify the accuracy of the estimated sample size.Results Simulation results showed that,when α =0.025 and α =0.01,the power of the sample size calculated by the formula is in accordance with the predetermined power.Conclusions The formula of sample size estimation we proposed could achieve the predetermined power for survival analysis in single-arm trials.Findings of this study provide reliable basis for sample size estimation of early stage antineoplastic drug clinical studies.