Sample Size Determination
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Difference between two means: estimate
This utility can be used to calculate required sample size when your aim is to estimate the difference between two sample means with specified precision.
Formula used and other details
Your guesstimate of first Sample mean (M1)
Required
Approxiate estimate of first Sample mean based on previous studies / pilot studies etc.
Your guesstimate of Standard Deviation of first Sample mean (SD1)
Required
Approxiate estimate of Standard Deviation of sample mean, based on previous studies / pilot studies etc.
Your guesstimate of second Sample mean (M2)
Required
Approxiate estimate of second Sample mean based on previous studies / pilot studies etc.
Your guesstimate of Standard Deviation of second Sample mean (SD2)
Required
Approxiate estimate of Standard Deviation of second sample mean, based on previous studies / pilot studies etc.
Ratio of Sample Size in two Groups (N2 / N1)
Enter number from 0.01 to 9.00
Required
Sample Size in Group 2 / Sample Size in Group 1
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.
Allowble error (precision)
Precision. Should be between 0 at the actual difference between means
Sample Size Required =