Sampling

• Random sample

  All members of a population have an equal chance of selection
• Systematic sample

  Every nth member selected eg every 5 people
• Stratified sampling

  When the sample has the same proportions of people as the population has
• Opportunity sample

  Anyone who enters selected because samples of target pop are difficult to obtain
• Volunteer sample

  Pps select themselves
• Pro of random sample

  Unbiased but time consuming
• Pro of stratified sample

  Generalisation of findings is possible, time consuming, sometimes its inaccurate on the proportions
• Pro of opportunity sample

  Convenient but there can be bias
• Pro of volunteer

  Easy, but there can be bias due to attracting a certain type of person