Study Notes
Types of Experiment: Overview
- Level:
- AS, A-Level
- Board:
- AQA, Edexcel, OCR, IB
Last updated 6 Sept 2022
Different types of methods are used in research, which loosely fall into 1 of 2 categories.
Experimental (Laboratory, Field & Natural) & Non experimental (correlations, observations, interviews, questionnaires and case studies).
All the three types of experiments have characteristics in common. They all have:
- an independent variable (I.V.) which is manipulated or a naturally occurring variable
- a dependent variable (D.V.) which is measured
- there will be at least two conditions in which participants produce data.
Note – natural and quasi experiments are often used synonymously but are not strictly the same, as with quasi experiments participants cannot be randomly assigned, so rather than there being a condition there is a condition.
Laboratory Experiments
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
Control – lab experiments have a high degree of control over the environment & other extraneous variables which means that the researcher can accurately assess the effects of the I.V, so it has higher internal validity.
Replicable – due to the researcher’s high levels of control, research procedures can be repeated so that the reliability of results can be checked.
Limitations
Lacks ecological validity – due to the involvement of the researcher in 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
These are typically carried out in a natural setting, in which the researcher measures the effect of something which is to see the effect of this on something else (D.V.). Note that in this case there is no deliberate manipulation of a variable; this already naturally changing, which means the research is merely measuring the effect of something that is already happening.
Strengths
High ecological validity – due to the lack of involvement of the researcher; 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.
You might also like
Field Experiments
Study Notes
Laboratory Experiments
Study Notes
Natural Experiments
Study Notes
Control of Extraneous Variables
Study Notes
Learning Approaches - Social Learning Theory
Study Notes
Research Methods in the Social Learning Theory
Study Notes