Calculate a Statistical Sample Size  Attribute Sampling
This calculator allows you to estimate the random sample size required to achieve a specified
level of statistical precision, or sampling error, in making a sample inference about a
population. The required input parameters are: (1) the population count; (2) the estimated
incidence rate of the attribute; and (3) your desired statistical precision, expressed as a
percentage of the population at a specified confidence level.
How to Use

Enter the Population Count.

Enter the Estimated Incidence Rate (of that population). Expected Incidence rate must be greater than zero. In the case of a population of
funded loans, the incidence rate may refer to the incidence of defective loans in the
population. Since we cannot know the actual defect rate of the population (that's why
we need to sample), this number must be an estimate. Because this is a important number,
it should reflect your best estimate; if you are unsure what to enter, consider
performing an initial pilot study with a small sample, then revisit the sample size
calculation using the pilot study's incidence rate.

Enter your Desired Precision Level and select a Confidence Level, either onesided or twosided. Precision Level must be greater than zero.

After you have entered all values, click on the Calculate button. The System will
calculate the sample size required to achieve the desired precision level. You may
change the entered values and click the Calculate button again to perform the
calculation based on the new values.