Summary Research methods and concepts

RESEARCH METHODS + CONCEPTS
EXPERIMENTS
 All experiments involve an IV + DV.
 The IV is varied to see how it affects the DV – demonstrating a
causal relationship.
 All other variables are controlled as far as possible so any changes
in the DV are due to the IV rather than extraneous variables.


LABORATORY EXPERIMENT –

 Lab experiment = an experiment conducted in a controlled
environment.
 Tends to have high internal validity because many extraneous
variables can be controlled.
 HOWEVER – some EV’s (e.g. experimenter effects + demand
characteristics) may reduce internal validity.
 Control also increases replicability, which is desirable.
 BUT – control reduces external validity because a highly controlled
situation may be less like the real world.


FIELD EXPERIMENT –

 Field experiment = an experiment conducted in a more natural
environment.
 It is more difficult to control extraneous variable than in a lab
experiment.
 Experimenter effects are reduced because participants are usually
not aware of being in a study.
 HOWEVER – demand characteristics may still be problematic, for
example the way an IV is operationalised may convey the
experimental hypothesis to participants.


NATURAL EXPERIMENT –

 Natural experiment = an experiment which makes use of existing
IV’s.
 An experiment involves the deliberate manipulation of an IV by the
experimenter, so causal conclusions cannot be drawn from a natural
experiment.
 Participants are not randomly allocated to conditions, so may reduce
validity.
 Sometimes it is the only way to study certain behaviours or
experiences (e.g. privation).