Stats

• Census measures every member of a population

  Advantages: accurate results

  Disadvantage: expensive / testing may destroy
• Sampling units: individual of a population

  sampling frame: lists of sampling units
• Random sampling

  Simple random sampling

  Systematic sampling

  Stratified sampling
• Non - random sampling

  Quota sampling

  Opportunity sampling
• Simple random sampling: Same chance of being selected and use a random number / lottery sampling

  Advantages: Bias free

  Disadvantages: need sampling frame
• Systematic sampling: take every k th unit , k = population / sample , pick a random number between 1 and k

  Advantages: quick to use

  Disadvantages: need sampling frame