Types of experiment Flashcards
What is a Laboratory experiment?
A controlled environment where EV and CV can be regulated.
The IV is manipulated and the effect of the DV is recorded.
What are the 2 strengths of lab experiments?
- EVs and CVs can be controlled
This means that the effect of EVs and CVs on the DV can be minimised, cause and effect between the IV and DV can be demonstrated, high internal validity. - Can be easily replicated
Greater contol means less chance that new EVs introduced, meaning that findings can be confirmed supporting their validity.
What are the 2 Limitations of lab experiments?
- May lack generalisability
The controlled environment may be rather artificial and participants are aware they are being studies, thus behaviour may not be natural and cant be generalised to every-day life, low external validity. - Demand Characteristics
These are cues in the experimental situation that invite a particular response from participants, the findings may be explained by these cues rather than the effect of the IV.
What is a field experiment?
A natural setting.
The researcher goes to participants.
The IV is manipulated and the effect on the DV is recorded.
What are the 2 strengths of Field experiments?
- More natural environment.
Participants more comfortable and behaviour more authentic.
Results may be more generalisable to everyday life. - Participants are unaware of being studied.
They are more likely to behave as they normally do so the findings can be generalised.
The study has greater external validity.
What are 2 limitations of Field Experiments?
- More difficult to control CVs/EVs.
Observed changes in the
DV may not be due to the
IV, but to CVs/EVs instead.
It is more difficult to establish cause and effect than in the lab. - There are ethical Issues.
Participants in a field experiment may not have given informed consent.
This is an invasion of participants’ privacy, which raises ethical issues.
What is a Natural experiment?
The experimenter does not manipulate the IV - it does change, but the change is not made by the experimenter - Someone or something else causes the IV to vary. The IV would have varied even if the experimenter wasn’t interested.
DV may be naturally occurring (e.g. exam results) or may be devised by the experimenter and measured in the field or a lab.
What are the 2 Strengths of Natural Experiments?
- May be the only practical/ ethical option.
It may be unethical to manipulate the IV, e.g. studying the effects of institutionalisation on children.
A natural experiment may be the only way causal research can be done for such topics. - Greater external validity.
Natural experiments involve real-world issues, such as the effect of a natural disaster on stress levels.
This means the findings are more relevant to real experiences.
What are the 2 Limitations of Natural experiments?
- The natural event may only occur rarely.
Many natural events are
‘one-offs’ and this reduces the opportunity for research.
This may limit the scope for generalising findings to other similar situations. - Participants are not randomly allocated
The experimenter has no control over which participants are placed in which condition as the IV is pre-existing.
May result in CVs that aren’t controlled, e.g.
Romanian orphans
adopted early may also be the friendlier ones.
What is a Quasi Experiment?
IV is based on a pre-existing difference between people, e.g. age or gender. No one has manipulated this variable, it simply exist.
DV may be naturally occurring (e.g. exam results) or may be devised by the experimenter and measured in the field or a lab.
What are the 2 Strengths of Quasi-Experiments?
1.There is often high control.
Often carried out under controlled conditions and therefore shares some of the strengths of lab experiments
This means, for example, replication is possible.
- Comparisons can be made between people.
In a quasi-experiment the
IV is a difference between people, e.g. people with and without autism.
This means that
comparisons between different types of people can be made.
What are the 2 Limitations of Quasi Experiments?
1.Participants are not randomly allocated.
The experimenter has
no control over which participants are placed in which condition as the IV is pre-existing.
Participant variables may have caused the change in the DV acting as a CV.
1.Causal relationships not demonstrated.
As with a natural
experiment, the researcher does not manipulate/control the IV.
We cannot say for certain that any change in the DV was due to the IV.
