Producing and Collecting Data

Question 1

What is a population in statistical terms?

Answer 1

Any large collection of objects or individuals, such as South Africans, students, or trees about which information is desired.

Question 2

Define a sample.

Answer 2

A representative group drawn from the population.

Question 3

What is sampling?

Answer 3

A technique of selecting individual members or a subset of the population to make statistical inferences from them and estimate characteristics of the whole population.

Question 4

What is a sampling frame?

Answer 4

List of potential individuals to be sampled.

Question 5

What is a representative sample?

Answer 5

A sample that has characteristics that are similar to the overall population.

Question 6

What does it mean for findings from a representative sample to be generalizable?

Answer 6

They should be equally true in the population from which the sample is drawn from.

Question 7

What is a sampling plan?

Answer 7

A method or procedure for specifying how a sample will be taken from a population.

Question 8

What characterizes a biased sampling plan?

Answer 8

It systematically favors certain outcomes.

Question 9

What are the two main types of sampling methods?

Answer 9

Probability methods and non-probability methods.

Question 10

What is probability sampling?

Answer 10

All units have a known chance of being selected.

Question 11

List examples of probability sampling methods.

Answer 11

• Simple random sampling
• Stratified sampling
• Cluster sampling
• Multi-stage sampling

Question 12

What is non-probability sampling?

Answer 12

Some units are unable to be selected.

Question 13

List examples of non-probability sampling methods.

Answer 13

• Quota sampling
• Convenience sampling
• Snowball sampling

Question 14

What is simple random sampling?

Answer 14

A sample selected in such a way that every possible sample of the same size is equally likely to be chosen.

Question 15

True or False: Simple random sampling eliminates bias.

Answer 15

True

Question 16

What is cluster sampling?

Answer 16

A method used when the population is naturally divided into groups, taking a simple random sample of groups.

Question 17

What is stratified sampling?

Answer 17

A method used when the population is divided into sub-populations sharing a common characteristic, with random samples drawn from each stratum.

Question 18

How does cluster sampling differ from stratified sampling?

Answer 18

In cluster sampling, whole groups are sampled, while in stratified sampling, random samples are taken from each group.

Question 19

What is volunteer sampling?

Answer 19

Individuals have selected themselves to be included.

Question 20

What is convenience sampling?

Answer 20

Individuals happen to be at the right time and place to suit the schedule of the researcher.

Question 21

What is purposive sampling?

Answer 21

Individuals are selected based on the researcher’s opinion or judgment.

Question 22

What is quota sampling?

Answer 22

The non-probability equivalent of stratified sampling, where strata and their frequency in the population are identified.

Question 23

What is snowball sampling?

Answer 23

A method used when there are difficulties in identifying members of the population or if the desired sample characteristic is rare.

Question 24

What is the priority when determining sample sizes?

Answer 24

To make sure the sample is representative of the population.

Question 25

How does sample size affect accuracy?

Answer 25

The larger the sample size, the more accurate the sample estimates can be expected to be.

Question 26

What are sampling errors?

Answer 26

Differences between the sample and the population that exist due to the observations selected for the sample.

Question 27

How can sampling error be reduced?

Answer 27

By having larger samples.

Question 28

What are non-sampling errors?

Answer 28

Errors that can include issues such as errors in data acquisition and selection bias.

Question 29

True or False: Increasing the sample size will reduce non-sampling errors.

Answer 29

False

Question 30

What are errors in data acquisition?

Answer 30

Arise from the recording of incorrect responses due to various factors such as faulty equipment or misinterpretation of terms.

Question 31

What is selection bias?

Answer 31

When the selection of subjects into a study leads to results that differ from what would have been obtained if the entire target population was enrolled.

Question 32

What is undercoverage?

Answer 32

Occurs when some members of the population are inadequately represented in the sample.

Question 33

What are nonresponse errors?

Answer 33

Occur when a large percentage of those sampled do not respond or participate.

Question 34

What is voluntary response bias?

Answer 34

Occurs when sample members are self-selected volunteers, potentially skewing the data.

Question 35

What is response bias?

Answer 35

Occurs when study participants do not respond truthfully or give answers they think the researcher wants to hear.