Experimental method
Population: the larger or entire group of individuals that the researcher wants to test.
Sample: smaller group from the population that is used in the research
• Must be representative of the populations i.e. have same personal characteristics for conclusions to be successfully drawn
Participants: the individuals in the study.

Research hypothesis (operationalized)
I  independent variable
P  population
O  operations (how it was measured)
D  dependant variable

Control group: the group of participants who were exposed to all variables except the IV
• This provides a standard performance that can be compared to experimental group in order to determine if the IV has had an effect of the DV
Experimental group: the group of participants that are exposed to all the variables including the IV
• Purpose is to determine if the IV has caused the DV

Independent variable (IV): has been deliberately manipulated/changed by the experimenter to determine if it has an effect on the DV.
Dependant variable (DV): is the part of a participant’s behaviour that has been measured/observed to test the effect of the IV.
Extraneous variables (EV): are any other variables other than the IV that may cause a change in the DV and affect the results
• When eliminated they are called Controlled variables
• Confounding variables: are uncontrolled variables that have an unwanted effect on the dv (can’t draw a clear conclusion on whether the IV actually caused the DV)

Examples of extraneous variables
• Participant variables: individual’s differences in characteristics may affect the results if not controlled. E.g. gender, age, ethnic group
• Order effect: participant may have prior knowledge of the task/experiment which may influence their performance. E.g. it may have improved the second time (practice effect), or impaired (boredom effect)
• Experimenter effect: rather than the IV, the unintended influence of the experimenter may cause changes in the participant’s behaviour.
• Placebo effect: changes may have been caused by their belief that they have been exposed to a treatment that would cause this effect
- Placebo = fake treatment
• Artificiality: unwanted effect on participant’s behaviour caused by their unnatural environment. E.g. in a laboratory setting.

Conclusions: decisions