Cohen (2013). Personality assessment: An overview

For laypeople, personality refers to components of an individual’s makeup that can elicit positive or negative reactions from others.

Personality refers to an individual’s unique constellation of psychological traits that is relatively stable over time. Personality assessment refers to the measurement and evaluation of psychological traits, values, interests, attitudes, worldviews, acculturation, sense of humour, cognitive and behavioural styles and related individual characteristics.

A personality trait refers to any distinguishable relatively enduring way in which one individual varies from another. The context in which behaviour is displayed is important in applying trait terms to behaviour. The trait is dependent on both the behaviour and the context in which the behaviour appears. Some behaviour might be governed more by societal expectations and cultural role restrictions than personality traits.

A personality type refers to a constellation of traits that is similar in pattern to one identified category of personality within a taxonomy of personalities (i.e. descriptions of people). A profile refers to a narrative description, graph, table or other representation of the extent to which a person as demonstrated certain targeted characteristics (i.e. personality traits) as a result of the administration or application of tools of assessment.

Type A personality refers to a personality characterized by competitiveness, haste, restlessness, impatience, feelings of being time-pressured and strong needs for achievement and dominance. Type B personality refers to a personality characterized by the opposite of type A personality.

Personality state refers to the transitory exhibition of some personality trait. A state is temporary.

There are several questions that need to be addressed in any overview of personality assessment and the approach differs per question: 

1. Why
   This depends on the goal of the personality assessment (e.g. selection).
2. Who
   Information about the personality can be obtained through self-report (1), an informant (2) or other measures (3).
3. What
   This is the question of what is being assessed when a personality test is conducted. This includes the specific areas a test is supposed to measure.
4. Where
   This is the question of where the personality assessment takes place.
5. How
   This is the question of how personality assessments are structured and conducted.

A self-concept measure refers to an instrument designed to yield information relevant to how an individual sees oneself with regard to the selected psychological variables. Self-concept differentiation refers to the degree to which a person has different self-concepts in different roles. A disadvantage of using raters (i.e. informant) is that it is unclear how neutral they are as they show the leniency error (1), generosity error (2), severity error (3), halo effect (4) and error of central tendency (5). The context of evaluation needs to be taken into account when using a rater. The cultural background of the person that is being assessed needs to be taken into account by the rater.

The response style refers to a tendency to respond to a test item or interview question in some characteristic manner regardless of the content of the item or question. The response style can affect the validity of the outcome. A validity scale is a subscale of a test designed to determine whether a faulty response style has been used.

The scope of a personality test refers to how much information it is supposed to yield about different aspects of personality. A personality theory can shape a test, although a personality test can also be atheoretical (i.e. not based on a particular theory). The advantage of an atheoretical tool of personality assessment is that test users can impose their own theoretical preferences on the interpretation of the findings.

Measures of personality vary in the degree of structure built into them (e.g. interview vs. structured interview). The frame of reference refers to the time frame and/or contextual issues that influence the focus of exploration (e.g. personality information about how a person is now or how a person wants to be).

The adjective checklist and the sentence completion format can be used to assess different frame of references.

Locus of control refers to a person’s perception about the source of things that happen to that person. The Q-sort technique refers to an assessment technique in which the task is to sort a group of statements. The statements may be sorted in ways designed to reflect various perceptions (e.g. ranking statements from most descriptive to least descriptive). The Q-sort technique is used to assess different frame of references.

The nomothetic approach to assessment is characterized by efforts to learn how a limited number of personality traits can be applied to all people. The idiographic approach to assessment is characterized by efforts to learn about each individual’s unique constellation of personality traits. The normative approach is an approach in which testtaker’s responses and presumed strength of a measured trait are compared to a larger population. The ipsative approach is an approach in which a testtaker’s responses and presumed strength of a measured trait are interpreted relative to the strength of the traits of the individual.

Issues with personality tests are bias (1), social desirability (2), the use of language (3) and different cultural groups and interpretations (4). There are several tools for the process of developing personality tests:

1. Logic and reason
   Logic can determine the content of the items of a test.
2. Theory
   Personality measures can differ in the extent to which they rely on a particular theory of personality.
3. Data reduction methods
   Personality measures can differ in the data reduction methods they apply (i.e. statistical techniques). This includes techniques such as factor analysis.
4. Criterion groups
   These are reference groups of test takers who share specific characteristics and whose responses to test items serve as a standard according to which items will be included in or discarded from the final version of a scale. This process of using criterion groups to develop test items is empirical criterion keying.

The content-oriented approach refers to the use of logic to determine the content of items in a personality test. A criterion refers to a standard on which a judgement or decision can be made.

Development of a test by means of empirical criterion keying has several steps:

1. Create a large, preliminary pool from which the test items for the final test will be selected.
2. Administer the pool to two groups of people: 1) a criterion group, 2) a randomly selected group of people.
3. Conduct an item analysis to select items indicative of membership in the criterion group.
4. Obtain data on test performance from a standardization sample of testtakers who are representative for the population.