A major aim of the social and behavioural sciences is to develop explanations
of various aspects of human behaviour. For example, we may be
interested in explaining why some people are more aggressive than others.
One way of determining the adequacy or validity of explanations is to
collect data pertinent to them and to see to what extent the data are
consistent with the explanation. Data agreeing with the explanation support
the explanation to the extent that they are not also consistent with
other explanations. Data inconsistent with the explanation do not support
the explanation to the extent that the variables relevant to them have been
appropriately operationalized. Operationalization involves either the
manipulation of variables or their measurement.