Sampling

Question 1

Convenience sampling

Answer 1

Selecting only the members of the population that are accessible (e.g. interviewing one’s grandparents)

Question 2

Volunteer sampling

Answer 2

Selecting members of the population who offer to participate in the investigation (e.g. creating an open-access online questionnaire)

Question 3

Quota sampling

Answer 3

Decide on a quota of units to be sampled from each subgroup of the population in order to obtain a more representative sample (e.g. invite at least 3 members from the major ethnic groups to participate in a focus group discussion)

Question 4

Simple random sampling

Answer 4

Giving each member of the population an equal chance of being selected for the investigation (e.g. rolling a dice and selecting from a list of possible questionnaire respondents)

Question 5

Advantages and disadvantages of probability sampling; random selection (Convenience, Volunteer, Quota)

Answer 5

Advantages: Reach out to more groups of the population

Disadvantages: Can also produce skewed results as units are sampled subjectively by the researcher.

Question 6

Advantages and disadvantages of non-probability sampling; convenience (Simple random)

Answer 6

Advantages: Cheaper, fairer, easier to administer

Disadvantages: Skewed sample, may result in higher costs

Question 7

Systematic random sampling

Answer 7

Selecting every nth element of the sampling frame, beginning with a randomly chosen point (e.g. roll a dice to determine sampling interval, if value is 5, select every 5th person from an ordered list of respondents to interview)

Question 8

Advantages and disadvantages of non-probability sampling; convenience (Systematic random)

Answer 8

Advantages: Better representation of the population as compared to random sampling

Disadvantages: Run the risk of sampling a part of the population that may share similar characteristics. e.g. corner flats as 5-room flats

Question 9

Proportionate stratified sampling

Answer 9

Total sample size is first determined. Next, sample size for each subgroup is determined in proportion to the proportion of that subgroup in the total population (e.g. if stratum is based on age, the sample size for the total population is 100, and the proportion of 60-69 year olds is 10% of the total population, the sample size for 60-69 year olds will be 10)

Question 10

Advantages and disadvantages of non-probability sampling; convenience (Proportionate stratified)

Answer 10

Advantages: Better coverage of the whole population, yields smaller sampling errors as compared to just using random or systematic sampling

Disadvantages: Some strata may be problematic to define e.g. age group ethnicity, census data may not be available