research methods

• Lab study

  These are conducted under controlled conditions, in which the researcher deliberately changes something (I.V.) to see the effect of this on something else (D.V.).

  Strengths

  lab experiments have a high degree of control over the environment + extraneous variables, so it has higher internal validity. helps to establish cause and effect between IV and DV

  Limitations

  Lacks ecological validity – researcher manipulating and controlling variables, findings cannot be easily generalised to other (real life) settings, resulting in poor external validity.
• Field Experiments

  These are carried out in a natural setting, in which the researcher manipulates something (I.V.) to see the effect of this on something else (D.V.).

  Strengths

  Validity – field experiments have some degree of control but also are conducted in a natural environment, so can be seen to have reasonable internal and external validity.

  Limitations

  Less control than lab experiments and therefore extraneous variables are more likely to distort findings and so internal validity is likely to be lower.
• Natural / Quasi Experiments

  Strengths

  High ecological validity – variables are naturally occurring so findings can be easily generalised to other (real life) settings, resulting in high external validity.

  Limitations

  Lack of control – natural experiments have no control over the environment & other extraneous variables which means that the researcher cannot always accurately assess the effects of the I.V, so it has low internal validity.

  Not replicable – due to the researcher’s lack of control, research procedures cannot be repeated so that the reliability of results cannot be checked.
• high concurrent validity is where there is close agreement between the data produced by the new test compared to the established test. Close agreement is indicated if the correlation between the two sets of data produced by the two tests exceeds +0.8