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Experimental methods - Coggle Diagram
Experimental methods
Natural Experiments
Natural experiments are logically similar to true experiments, but the situation happens by itself and so is completely uncontrolled by the researcher
Sometimes, for ethical or practical reasons, it is not possible for an experimenter to control and manipulate one of the variables under investigation. For example, it wouldn't be ethically correct to expose people to a lot of stress to investigate its effects. In such situations, a researcher may use a natural experiment.
Because natural experiments are not set up by the researcher, they always take place in participants' everyday surroundings such as their home or school.
In contrast to a true experiment or a quasi-experiment, the variable under investigation happens by itself and so is completely uncontrolled by the researcher. The researcher also has no control at all over who is in each 'experimental group'
Natural experiments are logically similar to true experiments in the sense that a variable happens and the researcher tries to measure its effects. For example, they could compare the educational outcomes of school pupils who experience a lot of stress versus those who do not
Quasi-Experiments
Quasi-Experiments are not true experiments because they lack control over the experimental groups used.
Sometimes it is not possible for an experimenter to randomly allocate participants to experimental groups. For example, if one of the variables under investigation is gender, people cant be randomly allocated to .'male' and 'female' conditions. A study is termed a quasi-experiment if it lacks random allocation to groups but is like a true experiment in most other ways
Other examples of quasi-experiments include studies which compare different types of personality or compare people who have a psychological disorder with a control group who do not. Such studies cannot randomly allocate people to groups.
Quasi-experiments could take place in a lab and all other aspects of the research and data gathering can be controlled.
Laboratory Experiments
Some experiments take place under controlled conditions, such as in a university room supervised by the researcher. These are called laboratory or lab experiments. The advantage is that they increase the level of control that a researcher can have. However, they reduce the level of ecological validity of the research.
Role in Psychology
Experiments play a major role throughout psychology. As a method, experiments allow one variable to be manipulated while keeping everything the same. This allows researchers to show cause and effect.
True Experiments
Both field experiments and lab experiments control the variables under investigation and randomly allocate participants to groups. These characteristics mean that they are true experiments.
Field Experiments
Other experiments take place in a participants natural surroundings, such as their school or workplace. The advantage of field experiments is that they increase ecological validity of the study by making the surroundings more realistic. But they reduce the level of control.