Statistical Solutions, LLC

Choose which calculation you desire, either to determine a power or a sample size. See more for the power of the test below.

This should be the "known" mean value for your population.

This should be the "expected" mean value from your sample. The delta between mu(0) and mu(1) is what you should consider a significant difference for the test.

This should be the known sigma (standard deviation) for the population.

Choose whether your test is based on one-sided or two-sided criteria. A single specification limit or pass/fail is one-sided, alternately an upper and lower specification is two-sided.

Enter a value for alpha (a)

(default is .05)

The outcome of the test depends on whether the null hypothesis (H0) is true or false and whether you reject or fail to reject it. When H0 is true and you reject it, you make a Type I error. The probability (p) of making a Type I error is called alpha (a), or the level of significance of the test. When H0 is false and you fail to reject it, you make a Type II error. The probability (p) of making a Type II error is called beta (b). See more on the Type I and Type II errors below.

Power of the test

(default is .80)

The power of a test is the probability of correctly rejecting H0 when it is false. In other words, power is the likelihood that you will identify a significant effect when one exists. If you are solving for power, leave this field blank. If you are solving for sample size, it is recomended to leave this field at the default value of .80 and the associated sample size will be generated when you click the calculate button.

If you are solving for sample size, leave this field blank. If you are solving for power, enter your desired sample size and the associated power will be generated when you click the calculate button..

Correct decision

p = 1 - a

Type II error

p = b

Type I error

p = a

p = 1 - b