Applied Statistics - 1.2 - Sampling

Question 1

What are the steps in simple random sampling?

Answer 1

• Number the list from 1 to the number of items
• Select x random numbers using a random number generator.
• Ignore repeats.
• Select corresponding items from the data sheet.

Question 2

What is systematic sampling?

Answer 2

The required elements are chosen at regular intervals from an ordered list.

Question 3

What is stratified sampling?

Answer 3

The population is divided into mutually exclusive strata and a random sample is taken from each.

Question 4

How should the proportion of the strata in stratified sampling correlate to the actual population?

Answer 4

The proportion of each strata sampled should be the same.

Question 5

What is the formula for calculating the number sampled in a stratum in stratified sampling?

Answer 5

Number sampled in a stratum = (number in stratum / number in population) x overall sample size.

Question 6

What are 2 advantages of simple random sampling?

Answer 6

• Free of bias
• Easy and cheap to implement

Question 7

What are 2 disadvantages of simple random sampling?

Answer 7

• Not suitable when the population size or the sample size is large.
• Sampling frame needed

Question 8

What are 2 advantages of systematic sampling?

Answer 8

• Simple and quick to use.
• Suitable for large populations

Question 9

What are 2 disadvantages of systematic sampling?

Answer 9

• It can introduce bias if the sampling frame is not random.
• Sampling frame needed

Question 10

What are 2 advantages of stratified sampling?

Answer 10

• Sample accurately reflects the population structure.
• Guarantees a proportional relationship of groups within a population

Question 11

What are 2 disadvantage of stratified sampling?

Answer 11

• Population must be clearly classified into distinct strata.
• Not suitable for large populations