Editing Psychological statistics (section)

====Validity====
{{Main|Test validity}}

Validity of a scale or test is ability of the instrument to measure what it purports to measure.<ref name=":1" /> [[Construct validity]], [[Content Validity]], and [[Criterion Validity]] are types of validity. 
Construct validity is estimated by convergent and discriminant validity and factor analysis. Convergent and discriminant validity are ascertained by correlation between similar of different constructs. 
Content Validity: Subject matter experts evaluate content validity. 
Criterion Validity is correlation between the test and a criterion variable (or variables) of the construct. [[Regression analysis]], [[Multiple regression analysis]], and [[Logistic regression]] are used as an estimate of criterion validity. 
Software applications: The [[R (programming language)|R software]] has ‘psych’ package that is useful for [[Classical test theory|classical test theory analysis]].<ref>Kline, T. J. B. (2005)Psychological Testing: A Practical Approach to Design and Evaluation. Sage Publications: Thousand Oaks.</ref>