Sampling is the process of selecting individuals from a population to be included in a sample.

Good sampling methods

  • Simple random sampling

\(\ominus\) Random number table

\(\ominus\) Random number in R, e.g., sample(1:20, 1)

  • Stratified sampling

  • Systematic sampling

  • Cluster sampling

Example How can we select a sample of 50 students from all freshmen enrolled in UNV 101 using the four different sampling methods?

Bias in sampling

Sources of bias

  • Sampling bias (e.g., convenience sample)

  • Nonresponse bias

  • Response bias