IPIP Neuroticism: Open-Access Big Five Measures and Their Limits
Author: Ukrainian Psychological Hub · Published: September 30, 2026 · Editorial Policy
IPIP neuroticism is not one universal test score. The International Personality Item Pool (IPIP) is a public-domain collection of personality items from which many different scales and inventories have been built. Some IPIP measures score the relevant Big Five dimension as Neuroticism, while Goldberg’s widely used Big-Five Factor Markers score the same broad territory in the opposite direction as Emotional Stability. The meaning of any IPIP neuroticism result therefore depends on the exact instrument, version, scoring key, response format, and reference group used.
The official International Personality Item Pool website currently describes more than 3,000 public-domain items and more than 250 scales. Its multi-construct inventory directory lists multiple Big Five-related measures, including Goldberg’s Big-Five Factor Markers, the Mini-IPIP, the Big Five Aspect Scales, the 300-item IPIP representation of the NEO PI-R, two distinct 120-item IPIP-NEO forms, and a 60-item IPIP-NEO short form. That variety is the central fact to understand before interpreting “an IPIP neuroticism score.”
Neuroticism itself is a modern dimensional personality construct, not a psychiatric diagnosis. For the broader trait definition, see Neuroticism: What It Is in the Big Five Personality Model. This article stays inside the measurement intent: what IPIP-based neuroticism measures are, how their scores work, what psychometric evidence supports particular versions, and where interpretation can go wrong.
IPIP Neuroticism: The Short Answer
If a result page says “IPIP neuroticism,” first identify the instrument. An IPIP-NEO-120 Neuroticism score, an IPIP-NEO-300 Neuroticism score, a Mini-IPIP score, a Big Five Aspect Scales Neuroticism score, and the Emotional Stability score from the 50-item Big-Five Factor Markers are not interchangeable numerical quantities. They may target overlapping personality territory while differing in items, scale length, lower-order structure, scoring direction, reliability, validation evidence, and norms.
A higher IPIP-NEO Neuroticism score generally means that the respondent endorsed more trait-like negative emotionality across the items in that particular inventory. A higher score on Goldberg’s 50-item Emotional Stability scale means the reverse: greater emotional stability and therefore lower standing on the neuroticism pole. The official IPIP site explicitly warns about online implementations that have mislabeled Emotional Stability as Neuroticism while retaining the Emotional Stability scoring direction; see its page on IPIP implementations.
No raw score, percentile, T score, or “high” label has a universal meaning outside its measurement context. The official IPIP project does not publish universal norms and recommends caution with canned normative tables; its norms guidance favors locally relevant reference distributions when appropriate. An online percentile is meaningful only relative to the data and algorithm used by that implementation.
What the International Personality Item Pool Actually Is
IPIP is best understood as a measurement resource rather than a single branded questionnaire. Goldberg and colleagues created a large public-domain pool so researchers could inspect, reproduce, translate, modify, and test personality items without the licensing barriers associated with proprietary inventories. The project’s current home page states that IPIP items and scales may be copied, edited, translated, or used without asking permission or paying a fee.
The foundational review by Goldberg and colleagues (2006) described the public-domain model as a major advantage for cumulative personality research, while also identifying a corresponding risk: unrestricted modification can produce idiosyncratic versions and fragmentation. Public-domain status answers a permissions question. It does not automatically establish that every website, translation, shortened form, scoring algorithm, or interpretation built from IPIP items has the same validity as a published scale.
That distinction explains why the phrase “IPIP test” can be misleading. There are established IPIP-based instruments, but there is no single IPIP questionnaire whose Neuroticism score can be assumed whenever a website uses the initials IPIP.
The Main IPIP-Based Ways Neuroticism Is Measured
Goldberg’s 50-Item Big-Five Factor Markers
One of the best-known IPIP instruments is Goldberg’s 50-item Big-Five Factor Markers, with ten items for each broad lexical Big Five factor. Crucially, factor IV is labeled Emotional Stability, not Neuroticism. On the official scoring key, positively keyed items include statements about being relaxed or seldom feeling blue, while negatively keyed items include stress, worry, being easily upset, mood changes, irritation, and feeling blue. After reverse-keying the negative items, a higher total indicates more Emotional Stability.
This makes directionality critical. If a website displays the 50-item factor-IV total under the label “Neuroticism” without reversing the scale direction, the label and number conflict. The IPIP project documents exactly this problem on its implementations page and recommends using the official keys.
Psychometric evidence exists for this specific scale. In three Scottish adult samples totaling 906 participants, Gow, Whiteman, Pattie, and Deary (2005) found a five-factor solution with minor discrepancies and reported strong convergence between the IPIP Emotional Stability/Neuroticism dimension and corresponding NEO-FFI and EPQ-R measures. Those findings support the construct validity of that 50-item marker set in those samples; they do not turn every derivative online implementation into an equivalent instrument.
The 300-Item IPIP Representation of the NEO PI-R
A different IPIP tradition uses public-domain items to measure constructs similar to the five domains and 30 facets of the NEO PI-R. The 300-item version contains ten items for each of 30 facet scales, with six facets contributing to each broad domain. In this inventory the relevant broad domain is Neuroticism rather than Emotional Stability.
The name “IPIP-NEO” can encourage an important mistake. An IPIP representation of NEO constructs is not the copyrighted NEO PI-R itself. It uses different items and does not inherit the NEO PI-R’s manual, norms, proprietary scoring system, or test identity merely because it targets similar constructs. Maples, Guan, Carter, and Miller (2014) directly examined convergence between the 300-item IPIP representation and the NEO PI-R and used that work to develop a 120-item IPIP-based measure. Convergence is empirical evidence of similarity; it is not instrument identity.
Johnson’s IPIP-NEO-120
John A. Johnson developed a 120-item public-domain short form by selecting four items for each of the 30 Five-Factor Model facets from the longer IPIP representation. The official IPIP scoring page for Johnson’s IPIP-NEO-120 shows six Neuroticism-related facet scales: Anxiety, Anger, Depression, Self-Consciousness, Immoderation, and Vulnerability, with four items per facet. The page reports internal-consistency estimates from a very large Internet sample and identifies the development article.
In the peer-reviewed development study, Johnson (2014) reported acceptable reliability for the 30 four-item facet scales in large Internet samples, convergence with the NEO PI-R and acquaintance ratings, and a facet factor structure closely resembling the NEO PI-R structure. The 120-item form substantially reduces respondent burden while retaining all 30 facet labels.
The shorter facet scales also mean that facet-level interpretation deserves more restraint than a long scale with more indicators. A domain score aggregates many items and is generally more stable than any one four-item facet. For an instrument-specific discussion of what the six NEO-style neuroticism facets mean, see Neuroticism Facets: Anxiety, Anger, Depression, Self-Consciousness, Impulsiveness, and Vulnerability.
Maples et al.’s 120-Item IPIP Measure
The official IPIP directory lists another 120-item NEO-oriented IPIP inventory developed by Maples and colleagues. It should not be silently treated as the same instrument simply because it has the same total number of items. Maples et al. (2014) tested the 300-item representation against the NEO PI-R and developed their own 120-item IPIP-based Five-Factor Model measure. When a study says “120-item IPIP” or “IPIP-NEO-120,” the citation and item key matter.
The IPIP-NEO-60
A still shorter IPIP-based form was developed using item response theory. Maples-Keller and colleagues (2019) created a 60-item representation using IPIP items and evaluated reliability, convergence, and criterion validity relative to established Five-Factor Model measures. The development illustrates a general psychometric tradeoff: fewer items reduce burden, but very short lower-order scales leave less information for fine-grained individual interpretation.
A 60-item score is therefore not a drop-in replacement for a 120- or 300-item score. Even when scales target the same broad domain, their raw-score ranges and measurement precision differ.
Mini-IPIP and Big Five Aspect Scales
IPIP also supports other Big Five operationalizations. The 20-item Mini-IPIP uses four items per broad trait. Donnellan, Oswald, Baird, and Lucas (2006) developed it as a short form of the 50-item IPIP Big Five measure and reported acceptable internal consistency, test-retest evidence, and convergent, discriminant, and criterion-related validity across five studies. It is efficient for broad domains, but it does not provide the same facet resolution as an IPIP-NEO inventory.
The 100-item Big Five Aspect Scales take another route. They divide Neuroticism into two broad aspects, Volatility and Withdrawal. The IPIP site provides the BFAS scoring keys, while the underlying model was developed by DeYoung, Quilty, and Peterson (2007). An aspect score should not be relabeled as a NEO facet score, and a NEO facet score should not be assumed to reproduce the aspect structure.
Why IPIP Neuroticism and Emotional Stability Can Look Reversed
Neuroticism and emotional stability commonly describe opposite poles of a closely corresponding Big Five dimension. The numerical direction, however, is instrument-specific. The 50-item lexical IPIP markers score factor IV as Emotional Stability, so higher values indicate greater stability. IPIP-NEO measures generally score the corresponding domain as Neuroticism, so higher values indicate more of the negative-emotionality trait.
This is not a cosmetic naming issue. Suppose two sites both show a score of 42. On a 10-item Emotional Stability scale whose raw range is 10 to 50, 42 is toward the stable end. On a different Neuroticism scale, 42 could occupy a completely different location because the item count, raw range, scoring direction, and reference distribution differ. A number without its instrument is incomplete information.
For a fuller explanation of the two poles and how major Big Five measures label them, see Neuroticism vs Emotional Stability: Two Ends of the Same Big Five Dimension?
How Standard IPIP Scoring Works
The official IPIP scoring instructions use a five-point response format from Very Inaccurate to Very Accurate. Positively keyed items receive values from 1 to 5 in the ordinary direction. Negatively keyed items are reverse-scored from 5 to 1. The item values are then summed to produce the scale total.
That procedure is simple, but three details still matter. First, the plus and minus keys are scale-specific; an item can only be scored correctly with the relevant published key. Second, a sum is not automatically a percentile or standardized score. Third, a developer can transform a raw sum into another metric, but the transformation and reference data must be documented before the result can be interpreted.
For the 10-item Emotional Stability scale in Goldberg’s 50-item markers, the standard summed raw-score range is 10 to 50. For Johnson’s 120-item IPIP-NEO, the Neuroticism domain contains six four-item facets, so a simple domain sum aggregates 24 responses. For the 300-item IPIP-NEO, six ten-item facets contribute substantially more item information. Those totals do not share a common raw-score metric.
What Does a High IPIP Neuroticism Score Mean?
On an IPIP instrument explicitly scored in the Neuroticism direction, a higher score means stronger endorsement of the characteristic negative-emotionality content represented by that scale. Depending on the version, this can include tendencies related to worry, anger, depressed affect, self-conscious distress, difficulty with urges, vulnerability under stress, withdrawal, or volatility.
The score is a trait estimate. It does not mean that every listed emotion is frequent, that every facet is elevated, or that the person will react strongly in every situation. Broad domain scores can conceal different lower-order profiles. Two people can reach a similar Neuroticism total through different combinations of facet scores.
A higher score also does not diagnose anxiety, depression, obsessive-compulsive disorder, post-traumatic stress disorder, a personality disorder, or any other clinical condition. Trait measures, symptom measures, screening tools, and diagnostic assessments answer different questions. IPIP neuroticism describes personality variation; it does not supply disorder-specific diagnostic criteria.
If the instrument is scored as Emotional Stability, reverse the verbal interpretation: a higher result indicates greater emotional steadiness and a lower position on the neuroticism pole. Always check the scale title and scoring key before interpreting direction.
There Is No Universal IPIP Neuroticism Cutoff
The most common interpretation error is to treat a raw number as if “high neuroticism” began at the same threshold everywhere. It does not. A cutoff can only be defined relative to an instrument and a rule for classifying scores. Different item counts create different ranges; different samples create different means and standard deviations; different websites can use different percentile algorithms or category bands.
The official IPIP project takes a notably cautious position. Its norms and data sets page says that no norms are provided on the IPIP website and warns that canned norms can be misleading when the comparison population does not match the sample of interest. The site recommends locally relevant norms when that is the defensible comparison.
Its individual-score interpretation guidance offers examples of sample-based interpretation, such as using a sample mean and standard deviation or quintiles, while explicitly cautioning against turning continuous trait scores into rigid personality types.
Large online datasets can still be useful. The IPIP norms page links Johnson’s open repository for the 300-item IPIP representation and the 120-item IPIP-NEO. But a percentile derived from an online volunteer sample describes standing relative to that reference distribution. It should not be presented as a universal population fact unless the normative design actually supports that claim.
Reliability and Validity: What the Evidence Does and Does Not Show
IPIP-based measures are sometimes described as “just free tests.” That understates the scientific literature. Several widely used IPIP instruments have substantial psychometric research behind them. At the same time, evidence attaches to a defined scale in a defined sample and administration context, not to the acronym IPIP in the abstract.
Reliability asks whether a score is measured consistently enough for its intended use. Internal consistency is one form of reliability; test-retest stability is another. Validity asks whether the score behaves as expected for the construct and purpose. A high Cronbach’s alpha alone does not prove that a scale measures neuroticism correctly, predicts a particular outcome, works equally across cultures, or is appropriate for individual clinical decisions.
For Goldberg’s 50-item markers, Gow et al. (2005) found good internal consistency and strong convergence of Emotional Stability/Neuroticism with corresponding NEO-FFI and EPQ-R scales in Scottish samples. For the Mini-IPIP, Donnellan et al. (2006) reported evidence across five studies. For the 300-item and 120-item NEO-oriented IPIP measures, Maples et al. (2014) and Johnson (2014) provide instrument-specific evidence. The 60-item form has its own development study by Maples-Keller et al. (2019).
These studies support the use of particular IPIP-based scales for personality measurement. They do not justify copying a subset of items, changing response options, altering item wording, using a new translation, inventing new cutoffs, or applying a scale to a different high-stakes purpose while assuming the original validation carries over unchanged.
The Limits of Open-Access and Public-Domain Measures
IPIP Is a Pool, So Version Control Matters
Freedom to adapt is one of IPIP’s strengths and one of its main measurement risks. A researcher can reorder items, combine scales, translate wording, or build a custom form. Once a measure changes, the evidence for the original scale may no longer describe the new version with the same precision. Reporting should therefore include the exact scale, citation, item count, response format, scoring method, language, and any modifications.
Online Implementations Can Differ
The official IPIP project notes that because the items are public domain, anyone can publish an implementation and the project cannot guarantee the quality or validity of implementations it did not oversee. Its implementations page documents both high-quality examples and a historically problematic Big-Five Factor Marker version whose labels and scoring created confusion. A polished interface is not evidence that the scoring key, norms, or interpretation is correct.
Norms Are Population-Dependent
Percentiles are comparisons, not intrinsic properties of a raw score. Age, language, culture, recruitment method, education, country, and other sample characteristics can affect score distributions. A percentile based on volunteer Internet respondents may be informative for that reference population while remaining imperfect as an estimate for a national population or a specific clinical group.
Translation Is a Measurement Question
Because IPIP items are public domain, translations are widely available. Translation freedom does not guarantee psychometric equivalence. A translated inventory should ideally be evaluated for wording, factor structure, reliability, validity, and—when cross-group comparisons matter—measurement invariance. Results from an English validation cannot simply be assumed to transfer unchanged to every language and culture.
Self-Report Has Built-In Constraints
Most IPIP measures discussed here are self-report questionnaires. They summarize how respondents describe their characteristic tendencies. Responses can be influenced by item interpretation, self-knowledge, response style, motivation, social desirability, fatigue, and current circumstances. Informant reports or repeated measurement can sometimes add useful information when the assessment purpose requires more than a single self-report snapshot.
Short Forms Trade Detail for Efficiency
A short form can be psychometrically useful while providing less item information than a longer measure. The Mini-IPIP is attractive when survey length is severely constrained; the 120-item IPIP-NEO preserves 30 four-item facets; the 300-item version devotes ten items to each facet. Choice should follow the purpose of measurement, not a blanket belief that shorter is inferior or that longer is automatically better.
A Personality Score Is Not a Clinical Diagnosis
IPIP neuroticism measures ordinary dimensional personality variation. They can be used in research on mental-health correlates, and neuroticism is associated statistically with many forms of psychological distress. That does not convert an IPIP score into a diagnostic cutoff. Diagnosis requires condition-specific clinical information, including symptoms, duration, impairment, context, exclusions, and differential assessment.
IPIP Neuroticism vs NEO PI-R, NEO-FFI, BFI-2, and Eysenck Measures
These instruments occupy nearby conceptual territory, but they should be named separately in research and interpretation.
IPIP-NEO versus NEO PI-R: IPIP-NEO measures were constructed from public-domain IPIP items to represent constructs similar to those in the NEO PI-R. The NEO PI-R is a distinct proprietary instrument with its own items, manual, norms, and scoring. Evidence of convergence supports construct correspondence; it does not make the scores interchangeable.
IPIP-NEO versus NEO-FFI: the NEO-FFI is a shorter NEO-family instrument focused on broad Five-Factor Model domains. An IPIP-NEO form that reports 30 facets contains a different level of detail. Neither raw-score system should be interpreted using the other instrument’s norms.
IPIP versus BFI-2: the BFI-2 is a separate 60-item Big Five inventory. It labels the neuroticism-related broad domain Negative Emotionality and organizes it into Anxiety, Depression, and Emotional Volatility facets. Soto and John’s BFI-2 development study established that instrument’s hierarchical 15-facet structure. The BFI-2 is not an IPIP scale, and its facet architecture should not be imposed on IPIP-NEO results.
IPIP versus Eysenck Neuroticism: Eysenck neuroticism scales arise from the PEN personality model rather than the Big Five/IPIP measurement system. Scores can correlate strongly because they capture related negative-emotionality variance, but item content and theoretical framework differ. A result should be reported under the instrument actually administered.
How to Read an IPIP Neuroticism Result Step by Step
Start with the exact instrument name. Look for wording such as 50-item Big-Five Factor Markers, Mini-IPIP, Big Five Aspect Scales, IPIP-NEO-120, IPIP-NEO-300, or another named IPIP scale. If the website only says “IPIP,” the result is underspecified.
Next check score direction. Is the scale called Neuroticism, Negative Emotionality, or Emotional Stability? In particular, confirm whether the 50-item factor-IV score is being reported in its original Emotional Stability direction.
Then identify the metric. A raw sum, item average, standardized z score, T score, percentile, and category label are different transformations. Ask what was transformed and against which distribution.
Check the reference group. A percentile has no meaning without a comparison distribution. Note whether the norms come from a local sample, a published Internet sample, a national standardization sample, or an undocumented website database.
Check the level of interpretation. A broad Neuroticism domain score is not the same as six NEO-style facets or two BFAS aspects. If a report makes precise claims about anger, self-consciousness, vulnerability, or withdrawal, verify that the administered instrument actually measured those lower-order scales.
Finally, keep the conclusion dimensional. The score estimates standing on a personality continuum. It should not be converted into statements such as “you have neuroticism,” “you are mentally ill,” or “you have an anxiety disorder.”
When Is an IPIP Measure a Good Choice?
IPIP measures are particularly useful when transparent item access, reproducibility, public-domain licensing, flexible research administration, or open measurement materials are important. Researchers can inspect the exact items and scoring keys and can build studies without purchasing proprietary test materials. That openness has made IPIP influential in personality science and education.
The best version depends on the research question. A brief broad-domain measure can work when personality is one variable among many and survey time is limited. A 120- or 300-item NEO-oriented IPIP inventory is more appropriate when facet-level structure matters. A local-language study should use a translation with evidence for the target population whenever possible.
For individual feedback, the same principles apply with stricter attention to norms and uncertainty. A transparent report should name the instrument, explain scoring direction, identify the reference group, describe the score as an estimate, and avoid clinical conclusions that the personality measure was not designed to support.
Frequently Asked Questions
What is IPIP neuroticism?
IPIP neuroticism refers to neuroticism-related personality scores produced by one of several instruments built from the International Personality Item Pool. There is no single universal IPIP neuroticism scale. The exact version and scoring key determine what the number means.
Is the IPIP a real psychological test?
IPIP is a public-domain item pool from which many psychological scales and inventories have been developed. Several named IPIP-based Big Five measures have peer-reviewed reliability and validity evidence. The scientific status belongs to the specific measure and use case, not to every test page that happens to reuse IPIP items.
Is IPIP neuroticism the same as the NEO PI-R?
No. Some IPIP inventories were designed to measure constructs similar to NEO PI-R domains and facets, but they use public-domain IPIP items and are separate instruments. They do not use the NEO PI-R’s proprietary items or automatically share its norms and scoring.
What is a high IPIP neuroticism score?
There is no universal raw-score cutoff. “High” must be defined for a specific instrument, score direction, version, and reference sample. On a Neuroticism-scored measure it generally means more of the trait relative to the chosen reference distribution; on an Emotional Stability-scored measure the direction is reversed.
Why does my IPIP result say Emotional Stability instead of Neuroticism?
Goldberg’s lexical Big-Five Factor Markers name factor IV Emotional Stability and score it in the stability direction. Many Five-Factor Model inventories use Neuroticism or Negative Emotionality for closely corresponding territory. The labels and direction should be preserved rather than silently swapped.
How is an IPIP neuroticism score calculated?
Under the standard IPIP procedure, responses to positively keyed items are coded 1 through 5, negatively keyed items are reverse-coded 5 through 1, and the keyed item values are summed. The exact items and number of items depend on the scale. A website may then transform that raw sum into a percentile or standardized score using its own documented reference data.
Are IPIP percentiles official?
Not in a universal sense. The official IPIP website does not provide a single normative system for all scales and cautions against inappropriate canned norms. Percentiles shown by a website belong to the reference sample and algorithm used by that implementation.
Is IPIP-NEO-120 better than IPIP-NEO-300?
They serve different practical priorities. The 120-item form reduces burden while retaining 30 facets with four items each. The 300-item form uses ten items per facet and therefore provides more item information for fine-grained facet measurement. The appropriate choice depends on purpose, sample, respondent burden, and required precision.
Can an IPIP neuroticism result diagnose anxiety or depression?
No. It is a personality-trait score, not a disorder-specific diagnostic assessment. Neuroticism is statistically related to anxiety and depression, but association and diagnosis are different. A personality score cannot establish symptom duration, impairment, exclusions, or a clinical diagnosis.
Can researchers freely use IPIP items?
Yes. The official IPIP project places its items and scales in the public domain and states that they may be copied, edited, translated, or used without permission or fees. Researchers should still cite the relevant scale and validation literature and clearly document any modifications.
Related Articles
Neuroticism Facets: Anxiety, Anger, Depression, Self-Consciousness, Impulsiveness, and Vulnerability
References
DeYoung, C. G., Quilty, L. C., & Peterson, J. B. (2007). Between facets and domains: 10 aspects of the Big Five. Journal of Personality and Social Psychology, 93(5), 880–896. https://doi.org/10.1037/0022-3514.93.5.880
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(2), 192–203. https://doi.org/10.1037/1040-3590.18.2.192
Goldberg, L. R., Johnson, J. A., Eber, H. W., Hogan, R., Ashton, M. C., Cloninger, C. R., & Gough, H. G. (2006). The International Personality Item Pool and the future of public-domain personality measures. Journal of Research in Personality, 40(1), 84–96. https://doi.org/10.1016/j.jrp.2005.08.007
Gow, A. J., Whiteman, M. C., Pattie, A., & Deary, I. J. (2005). Goldberg’s ‘IPIP’ Big-Five factor markers: Internal consistency and concurrent validation in Scotland. Personality and Individual Differences, 39(2), 317–329. https://doi.org/10.1016/j.paid.2005.01.011
Johnson, J. A. (2014). Measuring thirty facets of the Five Factor Model with a 120-item public domain inventory: Development of the IPIP-NEO-120. Journal of Research in Personality, 51, 78–89. https://doi.org/10.1016/j.jrp.2014.05.003
Maples-Keller, J. L., Williamson, R. L., Sleep, C. E., Carter, N. T., Campbell, W. K., & Miller, J. D. (2019). Using Item Response Theory to develop a 60-item representation of the NEO PI-R using the International Personality Item Pool: Development of the IPIP-NEO-60. Journal of Personality Assessment, 101(1), 4–15. https://doi.org/10.1080/00223891.2017.1381968
Maples, J. L., Guan, L., Carter, N. T., & Miller, J. D. (2014). A test of the International Personality Item Pool representation of the Revised NEO Personality Inventory and development of a 120-item IPIP-based measure of the five-factor model. Psychological Assessment, 26(4), 1070–1084. https://doi.org/10.1037/pas0000004
Oregon Research Institute. Converting IPIP Item Responses to Scale Scores. https://ipip.ori.org/newScoringInstructions.htm
Oregon Research Institute. Information about Norms and Data Sets. https://ipip.ori.org/newNorms.htm
Oregon Research Institute. International Personality Item Pool. https://ipip.ori.org/
Oregon Research Institute. Interpreting Individual IPIP Scale Scores. https://ipip.ori.org/InterpretingIndividualIPIPScaleScores.htm
Oregon Research Institute. Multi-Construct IPIP Inventories. https://ipip.ori.org/newMultipleconstructs.htm
Oregon Research Institute. Versions of IPIP Measures around the World Wide Web. https://ipip.ori.org/IPIPImplementationsAroundTheWeb.htm
Soto, C. J., & John, O. P. (2017). The next Big Five Inventory (BFI-2): Developing and assessing a hierarchical model with 15 facets to enhance bandwidth, fidelity, and predictive power. Journal of Personality and Social Psychology, 113(1), 117–143. https://doi.org/10.1037/pspp0000096