Sample Technique

• 7 Sampling Techniques:

  • Opportunity
  • Self Selecting / Volunteer
  • Random
  • Snowball
  • Systematic
  • Stratified
  • Quota
• Weaknesses of Opportunity Samples

  2 forms of bias:

  • Unrepresentative of the target population, drawn from a very specific area (e.g., on the Highstreet)
  • Researcher bias: researcher has complete control over the selection of participants
• What is an Opportunity sample


  Opportunity Sample

  • Researcher selects anyone who is

  readily available and willing to take

  part

  • Simply ask people who are willing and

  available (convenient)

  • Whoever is around at the time of the

  study

  Opportunity Sample
• What is a Volunteer Sample

  • Involves participants selecting themselves to be part of the sample (self-selection)
  • Researcher places an initial advertisement (magazine/newspaper/radio/email) asking for volunteers
• Strengths of a volunteer sample

  Strengths:

  • Easy, requires minimal input from the researcher, less time consuming
  • Ends up with participants who are more engaged, more so than someone who was stopped in the street.
• Strengths of an opportunity sample

  • Less costly in terms of money also
  • Convenient method
  • Saves time and effort
• Weaknesses of a Volunteer Sample

  • Volunteer bias: asking for volunteers may attract a certain profile/type of person, one who is more curious and likely try to please the researcher (issues with generalizability)
• What is a Random Sampling technique

  • All members of target population have an equal chance of

  being selected

  • Complete list of all members of target population are

  obtained

  • Names on list assigned a number

  • Sample selected though lottery method (i.e. names/numbers out of hat)
• Strengths of a Random Sampling technique

  • Reduces chances of a biased sample: extraneous variables should be equally divided between different groups, representing target population
  • Free from researcher bias– the researcher has no control over who gets selected