There are 3 main types of experimental methods that researchers use to investigate their Hypothesis.
This is the most controlled type of experiment that scientists use. It takes place in a lab setting where other variables can be limited.
Another way to see if the experiment is a Lab experiment is to see whether the independent variable is manipulated directly.
This is an experiment with a low-medium level of control as it is done in a public setting and the extraneous variables cannot be controlled so such a level.
The independent variable is also directly manipulated in a Field Experiment.
Just when you thought the key terms were simple! A quasi experiment is when the independent variable is naturally occuring.
An example of this is a well known experiment:
This is an experiment on whether schizophrenia influences the concentration level of someone who suffers from it.
In this case, the independent variable is whether the person has schizophrenia. This is naturally occurring.