Sampling + Ethics

• Target population - group of people who the researchers want to apply their results to

  Sample is a small number of people form the target population who take part
• Volunteer Sampling:

  They are self-selecting

  HOW:

  Could put poster up in canteen + wait for 50 students to volunteer
• Opportunity sampling:

  Researcher uses whoever is available from the target population at the time

  HOW:

  teacher could choose 2 classes to get 50 participants
• Random sampling:

  Every member of the target population has the same chance of appearing in the sample

  HOW:

  Names from hat - write down every name, place them in a hat and shuffle, blindfold an independent observer to draw names out and shuffle in between each go until all the names have been drawn

  
  

  Random number generator - Write down every name, link every name with a number and get an independent researcher to draw a set of numbers from the random number generator and match the numbers to participants
• Systematic sampling:

  You might take every Nth person from a list

  HOW:

  taking every 5th student's name from a register
• Stratified sampling:

  Take a certain number of people from sub-divisions of your population

  HOW:

  Identify the subgroups

  Calculate the required proportion needed from each group

  randomly select participants from each group

  randomly assign them to their experimental condition
• Random Sampling A03: Strength is that there is reduced researcher bias

  E: Researchers sometimes may choose certain participants to take part in their research as it may provide them with the results they desire. By randomising the selection of participants this removes this possibility and gives everyone an equal chance of taking part.

  C: adds validity as the researchers own bias and opinion will not impact the sample making it more representative of the population as everyone has an equal chance of being chosen.
• Random Sampling A03: STRENGTH

  I: representative sample

  E: more likely to get a varied selection of participants, rather than just choosing volunteers or available people - who may be similar for particular reason.

  C: population validity means the findings can be generalisable to the target population
• Random sampling A03: WEAKNESS

  I: time consuming

  E: takes more time to put names in a hat that it does to carry out opportunity sampling

  C: Qs validity as the researcher has had less time to spend on other parts of the research such as data analysis
• Opportunity sampling A03: STREGNTH

  I: quicker and easier to do

  E: researcher may use their psychology students as they are ready and willing to take part

  C: adds validity as researchers can get their sample much quicker + therefore spend the extra time on data analysis
• Opportunity Sampling A03: WEAKNESS

  I: less likely to be representative

  E: sample would not represent anyone who is outside this age group, therefore research cannot be generalised

  C: Qs population validity as it wont accurately represent your target population, if you only study who is available.
• Volunteer Sampling A03: STRENGTH

  I: quicker and easier to do

  E: Only have to produce an advert or poster for participants + they come to the researcher

  C: adds validity can spend more time on data analysis due to gathering quick sample
• Volunteer sampling A03: WEAKNESS

  I: less likely to be representative

  E: students aged 18-25 who study psychology and have high IQ are not representative of anyone outside this specific category

  C: Qs population validity as means your sample wont accurately represent target population.
• Systematic sampling A03: STRENGTH

  I: reduced researcher bias

  E: researcher is not in control of choosing participants cant choose participants they wish to take part

  C: adds validity as sample will be more generalisable to the target population as they have not been chosen by researcher themselves
• Systematic sampling A03: WEAKNESS

  I: less likely to be representative

  E: The system that has been chosen may be flawed and mean some participants are more or less likely to be selected than others - similar names in order on register

  C: Qs validity as findings cannot be generalised to the rest of the target population as only certain types of people are involved.
• Stratified sampling A03: STRENGTH

  I: most representative method

  E: By identifying the sub-groups + finding a participant from each one it is more likely to represent each section of the target population.

  C: adds validity as it has measured participants that are proportionate to the target population.
• Stratified sampling A03: WEAKNESS

  I: time consuming and difficult to do

  E: The development of sub-groups and finding enough willing participants is a time consuming job which will impact the sample size.

  C: Qs validity as it may be difficult to get a big sample size bc its time consuming.
• The right to withdraw

  • Participants should be informed of their right to withdraw from the study at any point + without reason
• Debrief

  • Occur after the study to ensure participants can ask any questions, receive access to counselling or therapy + reassure their results will be kept confidential.
• Deception

  • At the end of research experimenter should inform participants of the true nature of research in the debriefing
• Confidentiality

  • Anonymity must be maintained - using numbers or initials when writing up their names
• Informed Consent

  • Participants should agree + know every detail about the study

  1. Prior general consent: agree beforehand - knowing they will be lied to
  2. Presumptive consent: presumed that the real participants would also have agreed
  3. Parental consent: under age of 16 = parents
• Consent form:

  • Purpose of the investigation
  • The purpose of this study is...
  • Procedural information
  • If you agree to take part in this study, you will be asked...
  • Ethical information
  • Ethics e.g. confidentiality
  • 'Signature'