Editing Construct validity (section)

===Convergent and discriminant validity===
{{Main| convergent validity| discriminant validity }}
Convergent and discriminant validity are the two subtypes of validity that make up construct validity. Convergent validity refers to the degree to which two measures of constructs that theoretically should be related, are in fact related. In contrast, discriminant validity tests whether concepts or measurements that are supposed to be unrelated are, in fact, unrelated.<ref name="Campbell">{{cite journal | author = Campbell D. T. | year = 1959 | title = Convergent and discriminant validation by the multitrait-multimethod matrix | journal = Psychological Bulletin | volume = 56 | issue = 2| pages = 81–105 | doi=10.1037/h0046016| pmid = 13634291 }}</ref> Take, for example, a construct of general happiness. If a measure of general happiness had convergent validity, then constructs similar to happiness (satisfaction, contentment, cheerfulness, etc.) should relate positively to the measure of general happiness. If this measure has discriminant validity, then constructs that are not supposed to be related positively to general happiness (sadness, depression, despair, etc.) should not relate to the measure of general happiness. Measures can have one of the subtypes of construct validity and not the other. Using the example of general happiness, a researcher could create an inventory where there is a very high positive correlation between general happiness and contentment, but if there is also a significant positive correlation between happiness and depression, then the measure's construct validity is called into question. The test has convergent validity but not discriminant validity.