4.3 Choosing Non-probability vs. Probability Sampling


Strengths and Weaknesses of Basic Sampling Techniques

Technique Strengths Weaknesses

Non-probability Sampling


Convenience sampling


Least expensive, least time consuming, most convenient


Selection bias, sample not representative, not recommended for descriptive or causal research


Judgmental sampling


Low cost, convenient, not time consuming


Does not allow generalization, subjective


Quota sampling


Sample can be controlled for certain characteristics


Selection bias, no assurance of representativeness


Snowball sampling


Can estimate rare characteristics


Time consuming in the field research


Probability Sampling


Simple random sampling (SRS)


Easily understood, results projectable


Difficult to construct sampling frame, expensive, lower precision, no assurance of representativeness


Systematic sampling


Can increase representativeness, easier to implement than SRS


Can decrease representativeness


Stratified sampling


Includes all important subpopulations, precision


Difficult to select relevant stratification variables, not feasible to stratify on many variables, expensive


Cluster sampling


Easy to implement, cost effective


Imprecise, difficult to compute and interpret results

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