types of experiments

• lab experiment

  It takes place in a controlled/artificial environment in which the researcher manipulates the IV and records the effect on the DV.
• lab experiment: strengths

  - Control over EV & CV in which the researcher can ensure the effect on the DV is due to the manipulation of IV. This increases the internal validity of the experiment.

  - Replicable due to the high levels of control which ensures no EV's are introduced if it is repeated
• lab experiment: weaknesses

  -Lacks generalisation as the environment is artificial and not like everyday life which means ppts may behave in unusual ways and lower the external validity.

  - demand characteristics are likely

  - low mundane realism = tasks may not represent everyday life
• field experiment


  The IV is manipulated in a natural setting and DV's effects are recorded
• field experiment: strengths

  Higher mundane realism due to a more natural setting which may produce more valid and authentic results. Therefore increasing the external validity.
• field experiment: weaknesses

  - loss of control over the CVs and EVs which means it may be difficult to establish information and replication may not be possible

  -ethical issues as ppts can't give consent if they are unaware they are being part of a study which is an invasion of privacy
• natural experiment

  The change in the IV naturally happens and the researcher records the effect on the DV (someone or something can cause IV to vary)
• natural experiment: strengths

  - provides the opportunity for research which may not happen for practical or ethical issues

  - high external validity as it studies real-world problems and issues
• natural experiment: weaknesses

  - natural events may rarely happen which reduces opportunities for research

  - ppts may not be randomly allocated to experimental conditions

  - research may only happen in a lab which lacks realism and demand characteristics can be an issue
• Quasi experiment


  The IV has not been determined by anyone but it simply exists and can't be changed which means it is an existing difference in people.
• Quasi experiment: strengths

  - more ecological validity
• Quasi experiment: weaknesses

  - can't randomly allocate ppts to conditions which may cause CVs

  - IV is not changed by the researcher so we can't claim the effect on the DV is due to the IV