American Cancer Society
Please feel free to forward your comments, suggestions, and corrections to Dr. James L. Kepner

Sample Size Calculator: One-Sample Designs


This program determines the sample size necessary to attain a specified size and power for an exact test of one proportion. The hypotheses to be tested are of the form:

H0: p=p0
H1: p>p0
The user must submit a value for p0, an upper bound for alpha (i.e., the probability of committing a Type I error), and a lower bound for the power at the point p = p0+delta,   where 0 < delta < (1-p0).

Upon taking these study constraints into consideration, the calculator will then recommend a design that is optimal by the following criteria:
  1. The first stage sample size, n1, is as small as possible.
  2. The second stage sample size (if a two-stage design is requested), n2, is as small as possible and satisfies n2 <= n1.
  3. The third stage sample size, (if a three-stage design is requested), n3, is as small as possible and satisfies n3 <= n2.
  4. The actual significance level, or size, of the test satisfies size <= alpha, where alpha is the significance level specified by the user.
  5. The actual power at p = p0+delta, apower, satisfies apower >= power, where power is the user-specified minimum acceptable power.

Step One

Enter the following information from your study*:

Alpha   Power  
p0       Delta  

* Please note that computing time will be significantly increased when small values of alpha, beta, or delta are specified.

Step Two

Select type of study:

Step Three

Will this calculation take a significant amount of time?
No, Display Results
Yes, E-Mail Results
E-Mail Address:

Step Four

Click on the appropriate button:

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