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