Sampling

• what is a sample?

  when researchers try to make their research 'representative' of the population according to the type and number of participants used
• what is a target population?

  a specific group of people which the researchers are interested in studying, a smaller sample of this population can be taken called a sample
• why do psychologists take samples of the target population to investigate?

  Psychologists do this, hoping that the sample will be representative of the target population so that their results could be applied or generalised to them
• what is random sampling?

  • where everyone in the target population has an equal chance of being picked
  • + can get a perfect sample
  • rare as it's hard to get a population list
  • computer generated, pick a name out of a hat
• what is systematic sampling?

  • selecting participants at set points on a list
  • + ensures representative sample from each group like age, gender etc
  • rare as it's hard to get a population list
  • choose every 10th person on list e.g.
• what is opportunity sampling?

  • whoever able and willing to take part is chosen
  • + easy and practical
  • likely to produce biased results
  • ask family/friends/classmates etc
• what is stratified sampling?

  • researcher identifies different strata that make up the population, e.g. year groups, the proportion for that sample is worked out in order for it to be representative, participants make up each stratum selected using random sampling
  • + avoids researcher bias as one target population has been sub-divided into strata, the participants that make up the numbers are randomly selected
  • + generalisation is possible, representative sample
  • not perfect, sub-groups strata can't reflect all ways people are different, complete generalisation/representation not possible
• what is bias?

  • only viewing things from one perspective, without considering other possibilities.
  • psychologists try hard to be objective (rather than subjective), biases occasionally creep in.  This can be for many reasons, such as time, money, or because psychologists still have their own beliefs and opinions which sometimes get in the way of research
• what is gender bias?

  • Occurs when one gender is favoured over another.
  • Could happen if the research was based on male-only or female-only participants or if the researcher is the same gender as the participants, so may favour that gender.
• what is cultural bias?

  • Occurs when one culture is favoured over another. E.g. Western vs Non-Western cultures.
  • Could happen if the researcher’s perspective on findings is affected by their own cultural experiences or if researchers generalise their findings as universal without comparing different cultures
• what is experimenter bias?

  • Occurs when one theory is favoured over another, so the researcher sets up an experiment and interpret the results to fit the preferred theory