sampling

    Cards (18)

    • define target population
       The group of individuals that a researcher is interested in studying e.g. people in the UK.
    • define sampling frame
       A group/population that is identified when it is unrealistic to study the whole target population e.g. people in London.
    • define random sampling
       A sampling technique where participants are selected from the sampling frame, where everyone has an equal chance of being selected. E.g. Names are pulled out of a hat, or a computer is used to randomly select participants.
    • define opportunity sampling
       A sampling technique where participants are selected at the researcher’s convenience without knowing any details about the sample in advance e.g. picking people who were there at the time, in your specific location.
    • systematic sampling
       A sampling technique where every nth person on a list is selected by the researcher e.g. every 3rd house on a street, or 5th person on a register.
    • define stratified sampling
       A sampling technique where the target group is divided into subgroups, e.g. by sex, and then the participants are selected randomly from each subgroup.
    • define quota sampling
       A sampling technique where the target population is divided into subgroups, e.g. by sex, and the participants are chosen from each subgroup at the convenience of the researcher.
    • define self-selected sampling
       A sampling technique where participants volunteer (select themselves) for research e.g. they come forward/respond to the psychologist after reading an advertisement in a newspaper or on a notice board.
    • define snowball sampling
       A sampling technique where participants are initially recruited by the psychologist and then those participants recruit further participants from people they know, therefore the sample group appears to ‘snowball’.
    • what are observational sampling techniques
       A sampling technique that is used to collect data about specific behaviours or events within specific time frames.
    • define event sampling
      Where participants are observed by the psychologist, who records a specific behaviour (event) each time it occurs to create a total score.
    • time sampling
       Where the psychologist observes and records behaviour (such as a score) at specific time intervals, e.g. every 15 minutes, and then creates an average score for each participant being observed.
    • advantage and disadvantage of opportunity sampling
      • quicker than other sampling techniques - i.e stratified sampling don't need to know details about individuals beforehand
      • cost effective - money doesn't need to be spent on advertising.
      con:
      • open to researcher bias - may only select 'helpful' looking ppts.
      • likely to include sample bias- such as culture as they have only been selected from a narrow area.
    • advantage and disadvantage of self selected
      advantage- gives access to a wide variety of participants which make the sample more representative
      attrition is less likely
      disadvantage- volunteer bias, ppts more likely to be motivated and confident. so make it less representative of target population.
      may cost more to print adverts etc
    • random sampling advantages and disadvantages
      advantages- unbiased as all members have an equal chance of being selected.
      disadvantage- need a list of all members of target population, which may take time.
    • systematic sampling advantages and disadvantages
      • advantage- ppts selected using an objective system so it is unbiased.
      • disadvantage- not truly random unless starting with with a random method, start with this and then begin with every nth person.
    • stratified sampling advantage and disadvantage
      • sample is representative of population
      • however it is time consuming to identify sub groups, select them and calculated.
    • snowball sampling advantage and disadvantage
      advantage- enables researcher to locate groups who are difficult to locate
      disadvantage- may not be representative of target population due to bias.
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