Introduction to Various Big 5 Systems

Unlike some personality systems where someone originates the theory and every subsequent writer has to build on that theory, and attempts to totally re-engineer fundamental claims are viewed negatively (e.g. Carl Jung's work being the basis of MBTI theory) the big 5 is based on pure data and observation. The premise of the big 5 is that traits that correlate with one another can be grouped together into a small number of global traits. These systems do not group or measure the most prominent elements of human personality in the same way. They all use the same underlying methodology, which is based on grouping test items ("I like parties", I often feel sad" etc.) according to how people answer those tests and the degree to which those answers correlate.

Because these systems are all based on a principle of analysis rather than a source text (e.g. Psychological types, Gifts Differing) there is scope for a great range of disagreement about the optimal and most accurate way of organising these clusters of items, facets and traits. If a psychologist wants to construct a personality system along these lines, they simply need to run their study and present their data and the psychological community can choose to accept or reject their system and their findings based on the strength of their data and the legitimacy of the study's methodology. The exact structure of the big 5 is not set in stone. There is no source to which all subsequent versions must adhere, there is only the core principle of the appropriate and inappropriate ways to generate these various systems. If the reader wishes to know how to decide which version of the big 5 to use or what is the correct structure of the true big five personality traits (that is the underlying traits that exist in reality that these big 5 systems are all trying to capture as accurately as possible) then their safest bet is to familiarise themselves with several systems and note the ways in which these systems agree or disagree with each other. If you find a trait being defined one way in system A and another way in system B then the casting vote can go to whatever system C has to say on the matter. In this way you can develop your own sense on the consensus concerning this trait. Each of these systems represents the independent work of a distinct set of researchers. If system A makes a claim about the nature of Openness and systems B, C and D do not share that claim, it is reasonable to say that system A's claim does not represent the scientific consensus on the nature of Openness and can be regarded as a legitimate (because all the major big 5 systems are fundamentally legitimate pieces of research) but significantly lower quality indicator of openness than a claim that all 4 systems agree upon.

At the time of writing, this wiki contains descriptions for between 3 and 5 versions of the big 5 (depending on how you categorise them). It is recommended that the student of the big 5 familiarise themselves with all of these systems in order to develop the clearest and most balanced sense of how to conceptualise the major personality traits. As mentioned above, relying on one system alone can lead to you placing a lot of value in the conclusions of a system that is in conflict with the scientific consensus on the matter. By studying all these systems you can give yourself the best grounding in big 5 theory and will be able to present robust arguments for all your claims.

NEO

This is the oldest big 5 system still in use and dates back to the era from 1978-1985. It has been updated over time but the fundamental structure has not been modified. This is the best known and most widely used version of the big 5. It groups each trait into 6 facets. This is one of the more comprehensive versions of the big 5 and it covers things that are not covered at all in other versions: For example, Excitement seeking (extraversion) and Immoderation (neuroticism) are not mentioned in the other major versions of the big 5 and emotionality (openness) is actually mentioned in conjunction with other traits in other systems. So the NEO not only includes extraneous facets that are not included in other systems, it is also (on occasion) in direct contradiction with other systems. Other facets may be mentioned briefly in other systems but have a much lower level of significance: For example, Activity Level (extraversion) is hinted at by just one item in two other systems (BFAS and AB5C) despite constituting 1/6 of the total Extraversion trait in the NEO. So it is important to remember that not only is there disagreement about what should and should not be used as indicators of a given trait, there is also disagreement about the total value or significance of certain characteristics when calculating the score for a trait. By contrast, Friendliness (Extraversion) features in every version of the big 5 and so can be regarded as a more important or reliable trait indicator than those mentioned above.

As the NEO is one of the most comprehensive and most widely used versions of the big 5, you may want to use this system as your default whilst modifying its structure slightly. If certain facets are in clear conflict with other big 5 systems it would not make much sense to utilise those facets as if they were every bit as reliable as all the other traits. Applying the NEO as it was originally designed to be applied (with each facet constituting exactly 1/6 of its respective trait) will certainly not offer the optimal accuracy for calculating big 5 scores. However, if you wish to take the NEO as your default big 5 template and modify it so that it is more in accord with the other systems, exclude certain facets or adjust the weighting of certain facets, this should offer a way to generate highly accurate big 5 scores whilst still referring to the system that is most familiar to others. For example, scoring Openness as usual but simply excluding liberalism and emotionality from the score will offer a simple way to slightly raise the accuracy of your typing whilst still presenting your assessments in a system that others recognise.

NEO Domains

This is not really a distinct big 5 system from the NEO. It is by the same researchers and uses the same data but groups all the items into the most important items for each trait, without grouping those items into facets. This is a subtly different system to the NEO but is essentially the same system organised in a different manner. This does not appear to be a particularly significant system. The 6 facet version of the NEO is far more popular.

AB5C

This system dates from the mid 90s. Every big 5 item ("I have wild flights of fantasy" etc.) has some degree of correlation with each of the 5 traits. Generally speaking, items are used to indicate the trait with which they have the highest correlation, in order to establish an overall score for that trait. The basic method of the big 5 is to use these most highly correlated items to identify supposedly independent, distinct personality traits. AB5C takes a more complex approach and instead is structured in a manner that specifically identifies the top 2 most highly correlated traits for each item. For example, in most big 5 systems, the item "have fun" belongs to Extraversion, but in AB5C, this item belongs primarily to High Extraversion and secondarily to low Neuroticism. AB5C tells you not only the trait with which an item is most highly correlated but also the trait with which it is second most highly correlated. If you type someone who says they "like to have fun" or "People say I am lots of fun", with the other systems you might want to add a point to their extraversion score, whereas with AB5C, you might want to add a point to their extraversion score and also subtract half a point from their neuroticism score. This is a far more complex and challenging way of utilising the big 5. You may find that AB5C is a system that you refer to on occasion to try and place characteristics that don't quite fit within any one specific trait. It certainly is not the most helpful resource for new initiates but it is a useful resource nonetheless.

HEXACO

Arguably not a version of the big 5 because it technically has 6 traits, but in practice the underlying methodology is the same and most of the traits are virtually the same. The main difference is that Agreeableness has been divided into separate traits, Agreeableness and Honesty-Humility. There are some other small disagreements with the big 5 (e.g. Anger is featured more as a component of low agreeableness instead of high neuroticism). Because it divides the traits slightly differently this is again another system that is perhaps not the best choice for using as one's default big 5 system, but rather as a resource that can develop one's understanding of the big 5 and indicate the relative strength and importance of facets in each big 5 system. For example, the fact that anger is placed under agreeableness might lead you to place less value in anger when calculating someone's neuroticism and might even lead you to lower their agreeableness score slightly. Not every system in this Big 5 wiki can be used as a standalone system but all of them can be used to clarify the most accurate way to calculate big 5 scores. Every system is measuring the same subject (human personality) using the same method (mean item intercorrelations). If you wish to analyse someone as accurately as possible, the goal in applying the big five should be to use these systems to figure out the most accurate picture of the actual structure of human personality. This approach will optimise your understanding of human beings far more than dogmatically adhering to one version of the big 5 at the exclusion of all the others.

BFAS

The most modern version of the big 5 on this wiki, which dates from 2007. This one builds upon NEO and AB5C and uses these systems to find a level between facets and traits. 6 facets combine into 2 aspects, which combine into a single trait. This one excludes some of the more contentious facets from the NEO, facets not used in HEXACO or AB5C (e.g. Liberalism (openness)). It offers a more precise, more accurate, more focussed summary of the big 5 traits at the expense of being comprehensive. A BFAS result will tell you less about a person overall (because it measures fewer elements) but will give you a much more accurate and reliable summary of that person's big 5 tendencies (because it focusses on the most reliable or legitimate elements). This system is sometimes dismissed as being "shallow" but this isn't really fair. Each trait still summarises between 3 and 5 of the 6 NEO facets. It would be an error to assume that this "2 aspect" system is only covering 1/3 of the same personality territory as the "6 facet" system. It does undeniably cover less ground though. Some of the other systems (HEXACO and AB5C) would make poor choices as a default system. NEO and BFAS are your best options for a default system. NEO offers more expansive definitions with lower construct validity (the degree to which all these items and facets are accurately describing truly independent traits), BFAS offers a less comprehensive summary with higher reliability. Which of those two systems is the better choice is a subjective decision but it is worth simply pointing out that the BFAS is a much more modern system that draws on a much larger body of research than the NEO. It is also worth recommending to those users who wish to memorise a big 5 system rather than having to constantly refer back to resources. It is a lot easier to remember 10 aspects than 30 facets.