Sample Size In Clinical Trials In The Name Of God Sample size in clinical trials.

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Sample Size In Clinical Trials

In The Name Of GodSample size in clinical trials

IntroductionSample size in clinical trials

Fundamental PointSample size in clinical trials

Statistical ConceptsSample size in clinical trials

Liying XU (Tel: 22528716)CCTERCUHK

31st July 2002

Clinical Trial Writing IISample Size Calculation and Randomization

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.

What is ?

• is the minimum difference between groups that is judged to be clinically important– Minimal effect which has clinical relevance in

the management of patients– The anticipated effect of the new treatment

(larger)

The Choice of and depend on:

• the medical and practical consequences of the two kinds of errors

• prior plausibility of the hypothesis• the desired impact of the results

The Choice of and • =0.10 and =0.2 for preliminary trials that

are likely to be replicated.• =0.01 and =0.05 for the trial that are

unlikely replicated.• = if both test and control treatments are

new, about equal in cost, and there are good reasons to consider them both relatively safe.

The Choice of and • > if there is no established control treatment

and test treatment is relatively inexpensive, easy to apply and is not known to have any serious side effects.

• < (the most common approach 0.05 and 0,2)if the control treatment is already widely used and is known to be reasonably safe and effective, whereas the test treatment is new,costly, and produces serious side effects.

Dichotomous Response VariablesSample size in clinical trials

Paired Dichotomous ResponseSample size in clinical trials

Adjusting Sample Size to Compensate for NonadherenceSample size in clinical trials

Adjusting Sample Size to Compensate for NonadherenceSample size in

clinical trials

Two Independent SamplesSample size in clinical trials

Paired DataSample size in clinical trials

Sample Size for Repeated MeasuresSample size in clinical trials

Sample Size Calculations for “Time to Failure”Sample size in clinical trials

Sample Size for Testing “Equivalency” or Noninferiority of Interventions

Sample size in clinical trials

Sample Size for Testing “Equivalency” or Noninferiority of Interventions

Sample size in clinical trials

Sample Size for Cluster RandomizationSample size in clinical trials

Estimating Sample Size ParametersSample size in clinical trials

Multiple Response VariablesSample size in clinical trials

Sample Size In Clinical Trials In The Name Of God Sample size in clinical trials.

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