Statistical Sampling

Question 1

What does statistical sampling use (Mathematical)

Answer 1

Mathematical number tables to choose a sample which is free from bias

Question 2

What does statistical sampling use (Probability)

Answer 2

Probability theory to evaluate the results of the testing

Question 3

Examples of statistical sampling methods?

Answer 3

Random selection
Systematic selection
Value weighted selection

Question 4

What is random selection?

Answer 4

Process uses random number tables to select the items in the sample. Ensures all items in population have an equal chance of selection

Question 5

What does systematic selection involve?

Answer 5

Selecting items using a constant interval between selections, the first interval having a random start

Question 6

Example of systematic selection

Answer 6

If auditor has a population with 1000 items and requires a sample containing 200 items then the sampling interval is 5 (1000/200)

Question 7

How is systematic selection process carried out?

Answer 7

Random starting point within the first 5 is then determined (say 2) and the auditor will test every 5th item after item number 2 (is 2 then 7 and so on)

Question 8

What is value weighted selection

Answer 8

Population is randomly ordered and items are selected for sampling by weighting the items in proportion to their value

Question 9

Difference between statistical and non-statistical sampling?

Answer 9

Statistical sampling can be measured and controlled, not possible with non-statistical

Question 10

When can meaningful exploration only occur?

Answer 10

From a statistical sample which has been selected randomly