Sampling

• Representative Sample

  Participants in the sample are similar (gender, class, ethnic status, intelligence) to the population
• Random Sampling


  All the population has an equal chance of being selected to take part in the study
• Producing a Random Sample


  - Computer Generated

  - Names or Numbers in a Hat

  - Pin Technique
• Random Sampling Strength


  No researcher bias
• Random Sampling Weakness


  May not be a representative sample
• Opportunity Sampling


  Participants selected on who is willing & available at time of

  study
• Opportunity Sampling Strength


  Practically Efficient Way of Producing a Sample of Data Quickly
• Opportunity Sampling Limitations


  May not be representative > cant generalise

  Not random as sample chosen by researcher > Bias
• Systematic Sampling


  Every nth Member of Population Selected

  
  

  Divide Population by

  Sample Size (500÷25)

  Select Every 20th
• Volunteer sampling


  Self -selected

  
  

  People respond to an advert and come forward to take part.
• Volunteer sampling Strength


  Gathering the sample takes very little effort.

  It is therefore less time consuming than other methods
• Volunteer Sampling Weakness


  May not be representative > can't generalise

  A certain type of person will volunteer
• Stratified Sampling


  Strata in the population is identified, work out proportions and the sample randomly selected to match population.
• Stratified Sampling Strength


  Based on ratios so produces a truly representative sample
• Stratified Sampling Limitations


  Impractical and time consuming to identify strata in population
• Pilot Studies


  Pilot studies are small-scale practice investigations

  carried out prior to the main research.