Sampling and data collection in quantitative studies

Question 1

Distinguish between probability and non-probability sampling

Answer 1

❖Nonprobability sampling
o X random selection of elements
o rarely represent the population

❖Probability sampling
o random selection of elements: each element has an equal, independent chance of being selected.
o Allows researchers to estimate the extent of sampling error (difference between population values and sample values)

Question 2

advantages and disadvantages of probability sampling

Answer 2

▪ Advantages: Yields more representative samples than non-probability designs
▪ Disadvantages: Time consuming, labor intensive, and impractical
▪ The only reliable method of obtaining representative sample in quantitative studies

Question 3

advantages and disadvantages of non-probability sampling

Answer 3

▪ Advantages: Economical and convenient
▪ Disadvantages: Risk of sampling bias which leads to misleading results

Question 4

Types of Nonprobability Sampling— Quantitative Research

Answer 4

Convenience sampling
Advantage: Practical and convenient
Disadvantage: The available subjects may be atypical of the population
Snowball sampling
Advantage: Useful in identifying subjects with specific traits who are difficult to identify by ordinary means
Disadvantage: Risk of bias, as the sample tends to possess similar characteristics which are of the researcher’s interest
Quota sampling
Advantage: Ensures that diverse segments are adequately represented
Disadvantage: Shares many of the weaknesses of convenience sampling
Consecutive sampling
Advantage: Reduce the risk of sampling bias, and can deal with potential time-related fluctuations
Disadvantage: Shares the weaknesses of non-probability sampling
Purposive sampling
Advantage: —
Disadvantage: Provides no external and objective method for assessing the typicalness of the selected subjects

Question 5

Using probability sampling methods in quantitative research

Answer 5

Simple random sampling
Advantage: Not subject to researcher biases
Disadvantage: Time consuming and labor intensive, as it requires a complete listing of the population elements
Stratified random sampling
Advantage: Sharpens the precision and representativeness of the samples
Disadvantage: Requires even more resources than simple random sampling, impossible if information on the stratifying variables is unavailable
Cluster sampling
Advantage: Does not require a listing of all subjects within the population, more economical and practical when the population is large and widely dispersed
Disadvantage: Less accurate than simple and stratified random sampling
Systematic sampling
Essentially identical but more preferable than simple random sampling, because the same results are obtained in a more convenient manner

Question 6

Advantages of Questionnaires (Compared With Interviews)

Answer 6

• less costly
• advantageous for geographically dispersed samples.
• offer the possibility of anonymity, which may be crucial in obtaining information about certain opinions or traits.

Question 7

Advantages of Interviews (Compared With Questionnaires)

Answer 7

❖Higher response rates
❖Appropriate for more diverse audiences
o Some people cannot fill out a questionnaire.
❖Opportunities to clarify questions or to determine comprehension
❖Opportunity to collect supplementary data through observation

Question 8

Factors Affecting Data Quality in Quantitative Research

Answer 8

❖data collection procedure
❖Circumstances under which data were gathering
❖Adequacy of instruments or scales used to measure constructs
o Psychometric assessment evaluates the measure’s measurement properties.
o Reliability: extent to which scores are free from measurement error