My Reading on ASQ CQA HB Part V Part 2

Part VE
Simple random
Simple random sampling ensures that each item in the population has an equal chance of being selected.
Random number tables and computer programs can help make the sample selections.
Systematic sampling
Systematic sampling also ensures that each item in the population has an equal chance of being selected. The
difference here is that after the sample size is determined, it is divided into the total population size to
determine the sampling interval (for example, every third item). The starting point is determined using a
random number table. Several computer programs are available to help determine the sample size, the
sampling interval, the starting point, and the actual samples to be evaluated.
Reporting
It’s not difficult to plug numbers into a formula and calculate the results. Management likes to work with
numbers that have meaning and that put boundaries around a question or an error rate. This is where
statistical sampling comes in. With statistical sampling, auditors can state in the audit reports that ―we have 95
percent confidence that the purchase orders are being correctly processed.‖ Sample size depends on
confidence level and what the auditor wants to determine. Naturally, the larger the sample size, the more
accurate the estimate. For small populations, the sample size is corrected. Auditing by statistical sampling is
best suited to single-attribute auditing. However, once the item to be audited has been selected, many
attributes can be checked during the audit. A purchase order has many attributes that can be checked
simultaneously. In this way, one calculation for sample size can be used to report on many attributes. Standards
(discussed in the next section) or statistical formulas should be used to determine the appropriate sample size
given a required confidence level, such as 95% or 99%.
For more information concerning statistical sampling, Dodge- Romig or Bayesian sampling plans, and
binominal distributions, consult a comprehensive statistical textbook.
https://www.calculator.net/sample-size-calculator.html?type=1&cl=95&ci=5&pp=10&ps=1000&x=59&y=34
Charlie Chong/ Fion Zhang