sampling

• Random sampling


  Avoids bias, every item has an equal chance of being selected
• Random sampling method

  1. Use an arial photo

  2. Place a grid over it

  3. Use a random number generator to select coordinates

  4. Place a quadrat at each location

  5. Collect a number of samples from within each quadrat
• Systematic sampling

  Underlying structure to the way data is collected
• Systematic sampling method

  1. Lay out a transect

  2. At equal intervals (e.g. every 5/10m) take a sample
• Stratified sampling

  Population is split into separate groups, each group is further analysed