Compliance Audit Sample Size Calculator (Attributes#)
Use the following statistical sampling calculator to create your own risk-based compliance auditing plan by entering the appropriate population and reliability statistics in the designated fields. The required sample-size will be calculated automatically for each risk category. Learn more here.
Request a download link for our risk-based sample-size calculator by entering your name and email address below.
About Sampling Calculator
The above statistical sampling calculator uses the Cochran formula to calculate the sample size needed to measure the proportion of items in a large population with a specified level of reliability (confidence level) and precision (confidence limit).
Where p is the (estimated) proportion of the population that has the attribute in question, and q is (1 – p). Z is found in a Z Table for a selected confidence level, and e is the desired margin of precision i.e. margin of error.
# With compliance attribute sampling the audit result is always binary i.e. either an item is compliant or it is not; there is no grey area.
- The above calculator is only to be used for attribute sampling where the population is large and the results of the audit are expressed as a percent of the population i.e. percent compliance or non-compliance.
- When an audit result is obtained statistically it is possible to state with a stipulated degree of confidence that the collected statistic also applies proportionately to the unsampled portion of the population.
An audit conducted with a 95% confidence level returns a sample statistic of 25% with a confidence interval of 5%. On the basis of this result, it can be stated that there is a 95% probability (confidence level) that the true population parameter resides between 20% and 30%.