Variables Sampling

Question 1

What is the formula to obtain the sample size for probability proportionate to size (PPS) sampling?

Answer 1

n = reliability factor (from PPS tables) × Book value / Tolerable error

Question 2

List the items that are inversely related to sample size in variables sampling.

Answer 2

Allowance for sampling risk
Risk of incorrect acceptance (Type II error)
Risk of incorrect rejection (Type I error)

Question 3

List the items that are directly related to sample size in variables sampling.

Answer 3

Estimated population standard deviation

Population size - considered explicitly in variables sampling

Question 4

What is the basic sample size formula?

Answer 4

Sample size = (Estimated population standard deviation × Coefficient of reliability × Population size / Allowance for sampling risk) squared

Question 5

What is the purpose of stratification?

Answer 5

To reduce the overall variability within a population

Question 6

List the two parameters of a normal distribution.

Answer 6

Mean

Variance

Question 7

List the various types of classical variables sampling techniques.

Answer 7

Difference estimation
Ratio estimation
Mean-per-unit estimation

Question 8

List the eight basic steps in variables sampling.

Answer 8

1. )Identify sampling objectives.
2. )Identify relevant population.
3. )Select specific sampling technique.
4. )Calculate the sample size.
5. )Determine selection method.
6. )Conduct the sample.
7. )Evaluate sample and project to population.
8. )Document the sampling procedures.