Paper 3

• Random sampling


  Everyone/thing have equal chance of being sampled

  Advantages - avoids bias & can be done with large population

  Disadvantages - leads to poor representation of people or area
• Stratified sampling


  Proportionate sample (e.g. 12 boys & 28 girls - sample more girls)

  Advantages - representative of whole population

  Disadvantages - size much be accurate & hard/rude to ask certain things
• Systematic sampling


  Chosen in regular way (e.g. every 3 people)

  Advantages - fair & good coverage

  Disadvantages - more biased (not equal chance of selection) & leads to over/under representation