Donnellan, M. B., Oswald, F. L., Baird, B. M., & Lucas, R. E. (2006). The Mini-IPIP scales: Tiny-yet-effective measures of the Big Five factors of personality. Psychological Assessment, 18, 192-203.
The Mini-IPIP is a concise assessment of the five factor model of personality. It contains only 20 questions and can usually be completed in less than five minutes, yet maintains good psychometric properties (see below). The test was created using items from the open source project called the International Personality Item Pool (IPIP).
In test theory, validation refers to the level of evidence that supports the ability of users to draw useful, accurate, and truthful inferences/interpretations from a measure. In other words, validity refers to an instrument measuring what it says it measures and the ability of results to generalize to real-world outcomes. Three types of validation include:
Ability to infer from test measures to larger construct domains; the degree to which the instrument measures all facets of what it says it measures
According to Donnellan et al. (2006), the Mini-IPIP is derived from the larger 50 item IPIP-FFM (see Goldberg, 1999) and was reduced to the top four items for each trait scale, using exploratory factor analysis as the primary method for selecting items that loaded most highly on a single trait [while maintaining balance between positive and negative keyed items]. The same study confirms that factor component loadings of the IPIP-NEO-120 are representative of the five major personality traits.
Ability to make inferences from test scores to another real-world behaviors
As summarized in Soto (2019), effect sizes between the five factors and important life outcomes are generally between r = .20 - .40 (p < .05 - .01).
Ability to make inferences from test scores to various psychological constructs (e.g., characteristics grouped as personality traits); the overall confidence that a test measures what it claims to measure
The five factor theory was popularized by Norman (1963) as an "adequate taxonomy of personality attributes" - it factor analyzed scores from various personality trait scales into five distinct factors. Later, a test called the NEO was created from this earlier body of work and used the familiar OCEAN trait categories: McCrae & Costa (1985) provided validation data for their NEO assessment.
Donnellan et al. (2006) document scale correlations between the Mini-IPIP and its longer-form parent assessment (average r = 0.9; see test characteristics table below). Confirmatory Factor Analysis indicated an acceptable fit: Root Mean Square Error of Approximation (RMSEA) = 0.07 (p < .05).
Reliability refers to the consistency and repeatability of test scores or measurements. It answers the question, how likely is an individual to obtain the same score if the same measure is repeatedly administered to them?
Assesses the degree of agreement between two or more raters in their appraisals.
Many studies have explored the extent that different observers ratings are different than self-ratings when evaluating the five factors. In particular, Kim et al. (2019) conducted a meta analysis of over 150 studies examining the degree that big five ratings from friends, family, colleagues, and strangers would differ from self-ratings. Overall, no significant differences were found (average effect δ = −.038) indicating good consistency between self and other ratings across various methods of assessment.
Assesses the degree to which test scores are consistent from one test administration to the next.
McCrae et al. (2010) indicates that the big five personality traits generally have strong retest stability when readministered to the same participants after 1 week (retest rs = .91-.93) and over the course of 6 years (retest rs = .87-.93). Trait consistency for Neuroticism, Extraversion, Openness, and Agreeableness peaks in middle age whereas Conscientiousness continuously stabilizes over time. Trait scores are also influenced by life events (Specht et al., 2011).
For the Mini-IPIP, Donnellan et al. (2006) found 3-week retest correlations of between rs = .62 (Agreeableness) to .87 (Extraversion).
Assesses the degree to which test scores are consistent when there is a variation in the methods or instruments used.
As demonstrated in Donnellan et al. (2006), convergent / scale correlations between Mini-IPIP and the following methods of measuring the five factors are relatively high:
Assesses the consistency of results across items within a test.
The alpha coefficient is a measure of reliability. It increases with fewer measurement errors of an assessment's items and when items are measuring a single construct.
Donnellan et al. (2006) reports alpha coefficients from a large college sample (n = 2,663) of users who completed the Mini-IPIP:
| Big-Five Domain | Items (+ / -) |
Coefficient Alpha |
Correlation with Parent Scale |
|---|---|---|---|
| I. Extraversion | 2 + 2 = 4 | 0.77 | .93 [.78] |
| II. Agreeableness | 2 + 2 = 4 | 0.70 | .89 [.67] |
| III. Conscientiousness | 2 + 2 = 4 | 0.69 | .90 [.67] |
| IV. Neuroticism | 2 + 2 = 4 | 0.68 | -.92 [.76] |
| V. Intellect | 1 + 3 = 4 | 0.65 | 0.85 [.56] |
| Total/Mean | 9 + 11 = 20 | 0.70 | .90 |
Adapted from the IPIP website