Experiments

• Outline the experimental method


  involves manipulating an independent variable to result in at least two conditions.

  A dependent variable is then measured across conditions to

  assess whether there is a difference in the results. If there is, the researcher can establish cause and effect.
• Identify the experimental designs.


  Independent groups, repeated measures and matched pairs.
• Explain what is meant by an independent groups design


  When different participants take part in each condition. This is typically used when comparing one group against another.
• Explain what is meant by a repeated measures design


  When the same participants take part in all conditions. This is typically used when comparing before and after results.
• Explain what is meant by a matched pairs design


  When different participants take part in each condition but the participants in each condition are matched on key variables that could affect the results e.g. their age.
• Describe the procedures of a matched pairs design


  Obtain a large enough sample to allow for successful matching.

  Match participants on key variables that could affect the DV e.g. by giving them a questionnaire and matching those with similar responses.

  Randomly allocate each member of a matched pair to the conditions using the hat method.

  Repeat the random allocation process for all matched pairs.
• Give two strengths of an independent groups design


  No risk of order effects as participants only take part in one condition so will not be affected by practice effects, boredom, fatigue etc.

  Low risk of demand characteristics as they only take part in one condition so are less likely to guess the aims.
• Give two limitations of an independent groups design


  High risk of participant variables as different people are being compared so their individual differences might affect the results.

  Also more time consuming as different participants take part in each condition so more participants are needed.
• Give two strengths of a repeated measures design


  No risk of participant variables as the same participants take part in each condition.

  Less time consuming as the same people can be used in each condition and so less participants have to be gathered.
• Give two limitations of a repeated measures design


  High risk of order effects as participants complete multiple conditions so their performance could be affected by practice.

  High risk of demand characteristics as participants take part in all conditions and so are more likely to guess the aims.
• Give two strengths of a matched pairs design


  No risk of order effects as participants only take part in one condition so will not be affected by practice effects.

  Low risk of demand characteristics as they only take part in one condition so are less likely to guess the aims.
• Give two limitations of a matched pairs design


  Participant variables may still remain an issue as the matching process may not be perfect.

  Also, the matching process is time consuming which delays the research process and increases research costs.
• Identify the types of experiments.


  Laboratory experiment, field experiment, natural experiment and quasi experiment.
• Explain what is meant by a laboratory experiment


  Refers to when the researcher manipulates the IV and measures the DV in a controlled environment where the behaviour would not usually occur.
• Explain what is meant by a field experiment


  Refers to when the researcher manipulates the IV and measures the DV in an environment where the behaviour being studied would naturally occur.
• Explain what is meant by a natural experiment


  The IV has not been manipulated by the researcher and is instead a naturally occurring event that has happened without the researcher’s

  involvement e.g. the loss of a job.
• Explain what is meant by a quasi experiment


  The IV has not been manipulated by the researcher and is instead a pre-existing difference in the participants that the researcher has no control over e.g. their age, sex etc.
• Give two strengths of a lab experiment


  Easy to replicate to check the reliability of the findings as it is conducted in a controlled environment.

  Also more ethical as participants are in an unnatural environment so are aware of being studied so can provide consent.
• Give two limitations of a lab experiment


  Lacks ecological validity as it is conducted in an unnatural environment and so may result in unnatural behaviour.

  It is at an increased risk of demand characteristics as participants are in an unnatural environment meaning they are aware of being studied so may attempt to guess the aims.
• Give two strengths of a field experiment


  High in ecological validity as it is conducted in a natural environment so may result in more natural behaviour.

  Is at a reduced risk of demand characteristics as participants are in their natural environment so may be unaware of being studied and therefore wont attempt to guess the aims.
• Give two limitations of a field experiment

  Difficult to replicate to check reliability as it is conducted in a natural environment where there is a lack of control.

  May also be less ethical - participants are in their natural environment so may be unaware of being studied so cannot consent.
• Give two strengths of quasi and natural experiments


  Allow for research where it would be impractical or unethical to manipulate the IV such as looking at the effect of sex (for a quasi experiment) or the effects of a pandemic (for a natural experiment). Also less time consuming as the researcher does not have to manipulate the IV or allocate participants to conditions.
• Give two limitations of quasi and natural experiments


  Can be difficult to replicate to check the reliability of the findings if the event/pre-existing difference is rare.

  They may also be at risk of participant variables as participants cannot be randomly allocated to the conditions.