- The researcher needs to control all possible variables, in order to test a hypothesis as accurately as possible.
- The way in which a researcher may affect the outcome of an experiment: the researcher’s expectations may (sometimes unconsciously) affect the response of the subjects.
- Getting informed consent from participants may affect the results; the participants’ experience should not be harmful, either during or after the experiment; one group should not be advantaged over another.
- Because of the high level of control, an experiment can be replicated easily; it is an objective method; it produces quantitative data.
- A high level of control means that what happens in the laboratory may not be true in the outside world; the small sample may not be representative; the participants may behave differently because they know they are in an experimental situation.
- Internal validity – if the results would be true for the participants outside the laboratory situation. External validity –if the results would be true for other individuals in the wider population.
- They both aim to test a hypothesis by manipulating one or more variables. Unlike the artificial laboratory environment, a field experiment takes place in natural surroundings.
- Advantages might be: it may be used to study the past; there are no potential ethical problems; it does not involve an artificial situation. Disadvantages might be: there is less control possible; there is more potential for experimenter effect.
