Ipsative

Ipsative literally means "of the self" (Latin derivation), and is used in psychology as in the phrase "ipsative measure" to indicate a specific type of measure in which respondents compare two or more desirable options and pick the one which is most preferred (sometimes called a "forced choice" scale). This is contrasted with measures that use Likert-type scales, in which respondents choose the score (e.g. 1 to 5) which best represents the degree to which they agree with a given statement (see also Norm-referenced test). "Ipsative Comparisons" are also sometimes used in standardized testing to compare significant differences in subtest scores.

Psychology

While mean scores from Likert-type scales can be compared across individuals, scores from an ipsative measure cannot. To explain, if an individual was equally Extroverted and Conscientious and was assessed on a Likert-type scale, each trait would be evaluated singularly, i.e. a respondent would see the item "I enjoy parties." and agree or disagree with it to whatever degree reflected their preferences.

If the same traits were evaluated on an ipsative measure, respondents would be forced to choose between the two, i.e. a respondent would see the item "Which of these do you agree with more strongly? a) I like parties. b) I keep my workspace neat and tidy." Ipsative measures may be more useful for evaluating traits within an individual, whereas Likert-type scales are more useful for evaluating traits across individuals. Additionally, ipsative measures may be useful in identifying faking.