To calculate a sample size for a hypothesis test about one standard deviation, specify the following quantities in the legacy calculator:
Alpha
The probability of a type I error, which is the probability of rejecting the null hypothesis when it is true. It is commonly referred to as the significance level of the test. The default alpha level is 0.05.
Hypothesized Standard Deviation
The hypothesized or baseline standard deviation to which the sample standard deviation is compared.
Alternative Standard Deviation
The direction of the change that you want to detect, either Larger or Smaller.
Note: If you select Smaller from the Alternative Standard Deviation menu, enter a negative Difference to Detect.
Specify two of the following values to calculate the third value:
Difference to Detect
The smallest detectable difference (how small a difference you want to be able to declare statistically significant). This is the difference between the hypothesized value and the true value.
Sample Size
The total number of observations (runs, experimental units, or samples) in your experiment.
Power
The probability of rejecting the null hypothesis when it is false. With all other parameters fixed, power increases as sample size increases.
Continue
Evaluates the missing value.
Back
Returns to the previous Sample Size and Power launch window.