Sampling methodology

Task goals

• Describe simple random, systematic, stratified, cluster, and convenience sampling, and identify which method a described scenario or sampling-frame diagram uses.
• Explain at least one advantage and one disadvantage of each of the five sampling methods.
• Calculate the correct number to sample from each stratum in a stratified sample, in proportion to stratum size.
• Explain why convenience sampling is quick and cheap but likely to produce a biased, unrepresentative sample.
• Explain why cluster sampling is practical for spread-out populations but risks being unrepresentative if the chosen clusters differ from the rest of the population.
• Judge which sampling method is most appropriate for a given real-world scenario, and justify the choice.