Research methods

• A confounding variable is an extraneous variable which affects both the DV and the IV, making it difficult to determine whether any change in the DV was due to the IV or not.
• An independent variable (IV) is the one being manipulated by the experimenter
• Blinding techniques, such as single-blind or double-blind procedures, are employed to reduce bias in both participants and researchers during an experiment.
• A variable is anything that can vary or change, e.g. age, gender, intelligence, mood, etc.
• The dependent variable is what is measured to see if it has changed as a result of changing the IV
• Control groups are used in experiments to provide a baseline for comparison, helping researchers determine the effect of the independent variable.
• Random assignment is a crucial aspect of experimental design in psychology, ensuring that each participant has an equal chance of being assigned to any group.
• The main ethical issues are: informed consent, confidentiality, deception, researcher bias, right to withdraw and protection from harm.
• Informed consent


  Participants should have sufficient information about research aims and procedures to be able to make an informed judgement. The researcher must tell the participants about all aspects of the study to obtain informed consent. However, this may influence their behaviour.
• The use of deception


  Participants should not be misled about the true aims, or have information withheld relating to the procedures of the study. However, they may show demand characteristics.
• Protection from harm


  Participants should be protected from any psychological or physical harm. The risks that they are exposed to within the research should not exceed what they would encounter in every day life. However, it is difficult to determine whether the risks do exceed.
• Random Sampling


  Every member if the target population has an equal chance of being selected for the sample.

  Strengths: no researcher bias, will be generalisable.

  Weaknesses: could be unrepresentative, not always practical.
• Systematic Sampling


  Involves taking every nth member of the target population to form the sample.

  Strengths: no research bias, will be generalisable.

  Weaknesses: Not truly representative.
• Stratified Sampling


  A small-scale reproduction of the target population, using random selection, participants are selected within each category in the proportions that they exist in the target population.

  Strengths: no researcher bias, would be genralisable.

  Weaknesses: requires a detailed knowledge of the target population, time consuming.
• Opportunity Sampling


  The researcher decides on the type of participant needed and approaches anyone who appears suitable.

  Strengths: relatively time and cost efficient.

  Weaknesses: likely to be biased, could be unrepresentative (which would then not be genralisable)
• Volunteer Sampling


  The researcher advertise for participants, who reply to the ad.

  Strengths: time and cost effective, could increase representativeness, less chance of them deliberately sabotaging the study.

  Weaknesses: likely to be unrepresentative.
• Aims


  Give research studies a clear focus, a general statement outlining what the researcher intends to investigate.
• Hypotheses

  A testable statement, which makes a prediction about the results. Researchers usually propose 2 hypotheses, once the research has analysed their data, they'll support one and reject the other.

  An experimental hypothesis: predicts that the IV will have an effect on the DV

  • directional (one-tailed)
  • Non-directional (two-tailed)

  A null hypothesis: the IV hasn't had an effect on the DV.
• Repeated Measures


  The same participants are used in each condition.

  Strength: Eliminates participant variables.

  Weaknesses: Order effects, Increases demand characteristics.
• Independent Groups


  Separate and different participants are used in each conditions.

  Strengths: Reduces order effects, Reduces demand characteristics.

  Weakness: Introduces participant variables.
• Matched Pairs


  Different participants are used in each condition but participants are matched on variables deemed relevant to the experiment.

  Strengths: No order effects, Less demand characteristics, Reduces participant variables.

  Weaknesses: Participants can't be exactly matched, Time consuming, Less economical.
• Experimental design

  • Repeated measures
  • Independent groups
  • Matched pairs