variable
anything that can vary/change within an investigation
independent variable
an aspect of the experimental situation that is manipulated or changes naturally so that the effect on the DV can be measured
dependent variable
measured by the researcher (any effect on the DV should be caused by the change in the IV)
experimental conditions
in order to measure the effect of the IV and the DV there must be different experimental conditions: the control condition and the experimental condition
operationalisation
where the variables are clearly defined in how they can be measured