•replication Repetition of an experiment to conﬁrm the results.
•theory A model of interconnected ideas and concepts that explains what is observed
and makes predictions about future events.
•hypothesis A speciﬁc prediction of what should be observed in the world if a theory
•research Scientiﬁc process that involves the systematic and careful collection of
•data Objective observations or measurements.
•variable Something in the world that can be measured and that can vary.
•operational deﬁnition The quantiﬁcation of a variable that allows it to be measured.
•experiment A study that tests causal hypotheses by measuring and manipulating
•independent variable In an experiment, the condition that is manipulated by the
experimenter to examine its impact on the dependent variable.
•dependent variable In an experiment, the measure that is affected by manipulation
of the independent variable.
•confound Anything that affects a dependent variable that may unintentionally vary
between the different experimental conditions of a study
•random assignment The procedure for placing research participants into the
conditions of an experiment in which each participant has an equal chance of being
assigned to any level of the independent variable.
•correlational study A research method that examines how variables are naturally
related in the real world, without any attempt by the researcher to alter them.
•third-variable problem When the experimenter cannot directly manipulate the
independent variable and therefore cannot be conﬁdent that another, unmeasured
variable is not the actual cause of differences in the dependent variable.
•descriptive study A research method that involves observing and noting the
behaviour of people or other animals in order to provide a systematic and objective
analysis of behaviour.
PSY100 Chapter 2 Research Methodology