Research Methods

Independent Variables

- factor or characteristic set by the researcher that is being investigates as a possible cause of a change in behaviour

- CAUSE

Dependent Variables

- factor or characteristic being measures that is thought to be affected by a change in the value of the IV

- EFFECT

Population

- complete set of individuals/participants under consideration from which a sample may be drawn

Sample

- subset of the population under investigation

Random Sample

- everyone in population has equal chance of being selected

- avoids bias

Random Stratified Sample

- used when researchers are interested in identifying characteristics that vary between groups of people in the population

- divide population into strata and then sample randomly from each strata

Opportunity Sample

- Participants selected from groups and regions that are readily available

- convenience sample

- has bias

Experimental Group

- exposed to treatment (IV present)

Control Group

- exposed to control condition (IV absent)

- provides a point of reference with which to compare experimental group

Random Allocation

- procedure for assigning participants to various groups in an experiment

- all participants have an equal chance of being allocated to either control or experimental group

- used to ensure participants in experimental group are similar to those in the control group

Placebo and Experimenter Effects

Placebo Effect

- participant expectation

- change in behaviour caused by the belief that one has taken a drug

- single blind procedure - participants do not know if they are in experimental or control group

Experimenter Effect

- changes in participants behaviour that are caused by the unintended influence of an experimenter

- experiment finds what it expects to

- Double blind procedure - neither the participant or the experimenter know what group the person is