What the Big Five personality traits actually predict

The Big Five (Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism) is the dominant academic personality framework. If you've taken it, you have a domain score and probably a percentile. But what do those numbers actually predict?

This is the page I wish existed when I first dug into this. Each section pulls the strongest, most-replicated effects from the meta-analytic literature. I'm avoiding the weaker, sexier-sounding correlations that don't replicate well.

Openness to Experience

What it measures: curiosity about ideas, art, novelty, abstraction. High = imaginative, intellectually curious, interested in unconventional ideas. Low = practical, conventional, prefers the tested.

What it predicts: - Education attainment. Strongest individual-difference predictor of completing college after IQ. The effect size is real — high-Openness adolescents are roughly 1.5–2× more likely to finish a bachelor's degree. - Creative output. The most reliable Big Five predictor of creative achievement (papers, art, patents). Effect sizes are moderate. - Political views. High Openness correlates with social-liberal views; low Openness correlates with social-conservative views. (The correlation with economic views is much weaker.) - Type of friend you'll click with. High-O people click most easily with other high-O people — they need novelty in conversation. Two low-O people also click well, but high-O / low-O pairings struggle past the first month.

What it does NOT predict: - General intelligence. Openness correlates ~0.3 with IQ — real but moderate. They're related, not the same. - Professional success outside creative fields. In ordinary jobs, Conscientiousness predicts performance better than Openness.

Conscientiousness

What it measures: orderliness, discipline, follow-through. High = organized, plans ahead, finishes what they start. Low = spontaneous, flexible, comfortable with messiness.

What it predicts: - Job performance, almost any job. This is the single most reliable Big Five → outcome correlation in the entire literature. Across thousands of studies, Conscientiousness predicts work performance with effect sizes in the 0.2–0.3 range — and unlike most other predictors, it works equally well across job types. - Longevity. Multiple longitudinal studies (most famously the Friedman lab's reanalysis of the 1921 Terman cohort) have found Conscientiousness as a strong predictor of how long people live. Mostly through behavioral pathways: Conscientious people exercise more, eat better, take medications consistently, drive safer. - Marital stability. Highest-Conscientiousness pairings have the lowest divorce rates. The effect isn't huge but it's consistent. - Financial outcomes. Predicts savings rates, debt levels, retirement preparation more strongly than IQ does.

What it does NOT predict: - Creativity. High-C people often struggle with the loose, unstructured exploration creative work needs. The relationship is roughly U-shaped — moderate Conscientiousness is best for creative output, while extreme Conscientiousness can hurt it. - Likability. High-Conscientious people are often described as reliable but not necessarily warm or fun. Likability tracks Agreeableness more than Conscientiousness.

Extraversion

What it measures: energy direction (toward people vs. internal life), social pace. High = outgoing, energetic, gets recharged by social contact. Low (introverted) = reserved, recharged by alone time.

What it predicts: - Subjective wellbeing. This is real and slightly uncomfortable: Extraversion correlates positively with self-reported happiness, life satisfaction, positive affect. The effect is small-to-moderate but very consistent. (Extraverts aren't necessarily deeper — they just self-report happier.) - Leadership emergence. When groups need a leader, the Extraverted person often gets the role. This is partly perception (Extraverts are seen as leader-y) and partly self-selection (Extraverts volunteer). - Sales and customer-facing job performance. Strong correlation, ~0.2–0.3. - Number of friends. Extraverts have more, on average. But — important — they don't necessarily have closer ones. Total friend count and average closeness measure different things, and the Extraversion correlation is much stronger with the first than the second.

What it does NOT predict: - Friendship quality, just quantity. Introverts and Extraverts report similar levels of friendship satisfaction in their actual friendships, even though Introverts have fewer. - Job performance in non-people-facing roles. Programming, research, accounting — Extraversion is roughly neutral or slightly negative.

Agreeableness

What it measures: warmth, trust, cooperation. High = warm, trusting, cooperative, kind. Low = direct, skeptical, willing to say the hard thing.

What it predicts: - Relationship quality. Marriages, friendships, parent-child — Agreeableness on at least one side of the dyad strongly predicts how the relationship goes. Two highly agreeable partners have the best outcomes; two low-Agreeableness partners struggle. - Income, NEGATIVELY. This is one of the most surprising and most-replicated findings: high Agreeableness is associated with lower income, especially in men. Low-Agreeableness people negotiate harder, leave bad jobs faster, and are more comfortable with conflict — all of which is rewarded financially. - Volunteering and altruism. Strong predictor of helping behavior, charitable giving, volunteer hours. - Conformity. High-Agreeableness people are more susceptible to social pressure (Asch-style conformity studies).

What it does NOT predict: - Job performance generally. Across most jobs Agreeableness is roughly neutral. There are field-specific exceptions (high-A is good in nursing and teaching, neutral-to-bad in trial law).

Neuroticism

What it measures: emotional reactivity, stress response. High = feels emotions intensely, weather inside changes fast. Low = steady, doesn't fluster easily.

What it predicts: - Mental health outcomes. Neuroticism is the single biggest individual-difference predictor of depression, anxiety disorders, and mood-related psychiatric conditions. Effect sizes are large (0.4+). - Physical health, NEGATIVELY. High Neuroticism predicts more physical-health complaints, even after controlling for actual disease incidence — partly because the relationship runs through chronic stress, which has real physiological effects, and partly because high-Neuroticism people notice and report symptoms more. - Relationship dissolution risk. High Neuroticism is the strongest single Big Five predictor of divorce. The mechanism is partly emotional reactivity and partly negative-attribution patterns. - Job satisfaction, NEGATIVELY. Across most jobs, high-Neuroticism people self-report less satisfaction, even when objective job conditions are similar.

What it does NOT predict: - Job performance, much. Despite the satisfaction effect, Neuroticism doesn't predict actual work performance very well. Many high-Neuroticism people perform fine — they just feel worse while doing it. - Intelligence. Neuroticism is essentially uncorrelated with IQ.

What this means for friendship matching

Most "personality matching" products average across all five domains and give you a single compatibility score. That's misleading.

The pattern that actually emerges in the literature: - Openness and Intellect: similarity matters most. High-O / low-O friendships struggle. - Agreeableness: at least one side high is the strongest pattern. Two low-A friendships are rare and tend to be brief. - Neuroticism: low-N is generally easier to befriend. High-N can match well with low-N or with another high-N who happens to share specific stress patterns. - Conscientiousness: less critical for friendship than for marriage. Rough similarity helps but isn't determinative. - Extraversion: surprisingly minor. Two introverts can be best friends, two extraverts can be best friends, mixed can be best friends. The one pattern that doesn't work is two extreme extraverts who both want to lead the conversation.

Are We Friends? builds on these patterns by ranking on 30 facets (the level below domains), weighted differently for friendship-relevant outcomes vs. general "similarity." That's the difference between matching on the five-factor signal vs. matching on what actually predicts whether two strangers become friends.

The full matching model is documented at /personality-based-friend-matching.