Sample Size Determination
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Clinical Trial: Superiority Design
This utility can be used to calculate required sample size for a clinical trial with superiority design when the outcome variable is in ratio scale.
Formula used and other details
Your guesstimate of Mean in test arm (M1)
Required
Approxiate estimate of mean in test arm based on previous studies / pilot studies etc.
Your guesstimate of Standard Deviation of mean in test arm (SD1)
Required
Approxiate estimate of Standard Deviation of mean in test arm, based on previous studies / pilot studies etc.
Your guesstimate of mean in control arm (M2)
Required
Approxiate estimate of mean in control arm based on previous studies / pilot studies etc.
Your guesstimate of Standard Deviation of mean in control arm (SD2)
Required
Approxiate estimate of Standard Deviation of mean in control arm, based on previous studies / pilot studies etc.
Ratio of Sample Size in two arms (Groups) (N2 / N1)
Enter number from 0.01 to 9.00
Required
Sample Size in Group 2 (control arm) / Sample Size in Group 1 (test arm)
Confidence Level %
Enter positive number between 0.01 to 99.99
Required
In percentage. Commonly used values are 95, 99 and 90. Should be between 0.01 to 99.99.
Power ( 1 - β)
Enter positive number between 0.01 and 99.99
Required
In Percentage. Should be between 0.01 to 99.99. Common values are 80 % and 90 %
Superiority Margin (d)
Required
It is the limit beyond control arm mean, which is used to define superiority of the test arm mean. Can be positive or negative depending on the direction of Supriority.
Superiority limit is positive, if superiority of test arm is defined when test arm mean is more than control arm mean. In rare situations, superiority of test arm is defined when test arm mean is less than control arm mean. In such rare situations superiority limit is negative.
One sided test
Being a superiority design, hypothesis test is always one sided
Sample Size Required =