In social science and psychometrics, construct validity refers to whether a scale measures the unobservable construct (such as "fluid intelligence") that it purports to measure. The unobservable idea of a unidimensional easier-to-harder dimension must be "constructed" in the words of human language and graphics. A construct is not restricted to one set of observable indicators or attributes. It is common to a number of sets of indicators. Thus, "construct validity" can be evaluated by statistical methods that show whether or not a common factor can be shown to exist underlying several measurements using different observable indicators. This view of a construct rejects the operationist past that a constuct is neither more nor less than the operations used to measure it.