Validity
Validity is the extent to which a test or instrument measures what it is supposed to measure. In other words, are the findings true? In evaluation, the goal is to use measurements that are as valid as possible. We might ask questions such as: does the evaluation answer the questions it is designed to answer? Are the results accurate? For example, a bathroom scale that accurately measures your weight is a valid instrument.
There are many different types of validity, such as construct validity, content validity, and face validity.
See also: reliability