Clinical Trial Writing Sample size calculation and Randomization lying XU (Tel: 22528716 CCTER CUHK 31Juy2002
Clinical Trial Writing II Sample Size Calculation and Randomization Liying XU (Tel: 22528716) CCTER CUHK 31st July 2002
Sample Size Planning
1 Sample Size Planning
1.1 Introduction ■ Fundamental points Clinical trials should have sufficient statistical power to detect difference between groups considered to be of clinical interest. Therefore calculation of sample size with provision for adequate levels of significance and power is a essential part of planning
1.1 Introduction ◼ Fundamental Points ◼ Clinical trials should have sufficient statistical power to detect difference between groups considered to be of clinical interest. Therefore calculation of sample size with provision for adequate levels of significance and power is a essential part of planning
Five Key Questions Regarding the sample Size a What is the main purpose of the trial? What is the principal measure of patients outcome? How will the data be analyzed to detect a treatment difference?(The test statistic: t-test X2orC工 a What type of results does one anticipate with standard treatment? h and h how small a treatment difference is it important to detect and with what degree of certainty?(8, a and B) How to deal with treatment withdraws and protocol violations. (Data set used
Five Key Questions Regarding the Sample Size ◼ What is the main purpose of the trial? ◼ What is the principal measure of patients outcome? ◼ How will the data be analyzed to detect a treatment difference? (The test statistic: t-test , X2 or CI.) ◼ What type of results does one anticipate with standard treatment? ◼ Ho and HA, How small a treatment difference is it important to detect and with what degree of certainty? ( , and .) ◼ How to deal with treatment withdraws and protocol violations. (Data set used.)
SSC: Only an Estimate Parameters used in calculation are estimates with uncertainty and often base on very small prior studies a Population may be different Publication bias--overly optimistic a Different inclusion and exclusion criteria a Mathematical models approximation
SSC: Only an Estimate ◼ Parameters used in calculation are estimates with uncertainty and often base on very small prior studies ◼ Population may be different ◼ Publication bias--overly optimistic ◼ Different inclusion and exclusion criteria ◼ Mathematical models approximation