Intelligence is a better predictor of job performance than having a conscientious personality

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Personality psychologists tend to divide personality into five core dimensions: openness to experiences, agreeableness, extraversion, conscientiousness, and emotional stability.

Any guesses as to which dimension might be most predictive of occupational performance? If you guessed extraversion, you’d be wrong. If you guessed emotional stability, you’d be wrong again.

The truth is that 100+ years of psychological research has shown conscientiousness – that is, the tendency toward self-efficacy, orderliness, achievement, and self-discipline – to be the best predictor of job performance. New research forthcoming in the Proceedings of the National Academy of Sciences offers an in-depth examination of why this is the case, and when it might not be true.

A team of scientists led by Michael Wilmot of the University of Toronto conducted a meta-analysis of 92 studies to explore the relationship between conscientiousness and various occupational variables (for example, on-the-job competence, procrastination, leadership, organizational commitment, adaptability, job satisfaction, and burnout, to name a few).

Across variables, the researchers found strong evidence to support the view that conscientiousness is highly predictive of job performance.

“Conscientiousness refers to individual differences in the tendency to be hard- working, orderly, responsible to others, self-controlled, and rule abiding,” state Wilmot and his team. “We present the most comprehensive, quantitative review and synthesis of the occupational effects of conscientiousness available in the literature. Results show conscientiousness has effects in a desirable direction for 98% of variables [...], indicative of a potent, pervasive influence across occupational variables.”

Although the relationship between conscientiousness and job performance is robust, the researchers identified some interesting caveats and boundary conditions. For example, they found that conscientiousness is a weaker predictor of job performance in “high-complexity” occupations (think, for instance, of professions that require a high degree of brain power such as an analyst or lawyer). It is the low- to moderate-complexity occupations – for example, customer service jobs – that are particularly well suited to the conscientious personality.

Furthermore, the researchers found that individuals high in conscientiousness do better in Health Care than, say, Law Enforcement (although conscientious individuals show above average job performance in both occupational sectors). The graph below reveals the job sectors in which conscientious individuals are most likely to excel, with Health Care leading the pack.

"Summary of meta-analyses of conscientiousness and occupational performance [...]. Diamonds ... [+] represent estimated population correlations corrected for unreliability. Horizontal bars are 80% credibility intervals around each population correlation."

The researchers suggest that organizations should do more to harness conscientious workers’ aptitudes and motivations. According to their analysis, conscientious individuals are motivated by status, acceptance, and predictability. Building organizational frameworks that allow conscientious individuals to pursue these needs is critical to maximizing their occupational potential.

The authors conclude, “Few individual differences variables have occupational effects as potent and pervasive as conscientiousness. Based on evidence from more than a century of occupational research, the vast treasure trove of findings [...] should motivate every individual, organizational, and societal decision maker to better understand, develop, and apply the valuable human capital resource that is conscientiousness.”

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Work occupies a disproportionate part of our lives. And, of course, we want to be good at the things we spend a lot of time on, so work performance is top of mind for many people. Yet with constantly shifting performance management systems piled on top of new pre-hire assessments being introduced seemingly every day, it can understandably feel like making sense of one’s job performance is futile.

Surely with such a difficult task as understanding and measuring job performance, it would then seem impossible that over 35% of job performance across a broad range of skilled roles could be explained by just two factors that can actually be measured in just 13 minutes. That might sound fanciful were it not for the fact that Frank Schmidt and John Hunter, two famous researchers in the field of Industrial-Organizational Psychology, teamed up to figure out what consensus has emerged from nearly a century of research on pre-hire assessments.

By way of background, pre-hire assessment methods can run the gamut from familiar techniques, like reference checks, to more obscure techniques, like graphology (more on that later). The purpose of these assessments is generally to predict future job performance—that is, to see if a potential employee will do well if he or she is eventually hired. While hiring managers may not want to predict only job performance, it is certainly sensible that this would be one of the key dimensions they are concerned with before making hiring decisions, as good job performance can spill over into other meaningful metrics, such as more promotions, increased job satisfaction, and longer tenure.

So, what is the first attribute that explains job performance in the quickest, lowest cost manner across a variety of skilled jobs? The answer may be surprising to some: general mental ability (GMA), commonly referred to as IQ. Schmidt and Hunter, in a separate paper, further explicate that the reason intelligence leads to better job performance is because more intelligent people, by definition, acquire job knowledge quicker. Drawing on a previous study of over 32,000 employees, the authors conclude that intelligence can explain about 26% of job performance differences between people in “medium complexity” jobs. Perhaps unsurprisingly, the more complex the job is (e.g., rocket scientist), the more intelligence plays a part in job performance.

Aside from intelligence, the second attribute that, over and above IQ, helps effectively and efficiently predict job performance is conscientiousness. Conscientiousness, simply stated, is hard work, although it can be broken down into additional dimensions (e.g., dependability, orderliness). Adding in a measure of conscientiousness on top of IQ allows one to explain about 36% of a potential new hire’s eventual job performance in a medium complexity job!

But surely to get these measurements of IQ and conscientiousness, one needs to sit in a windowless room with only a #2 pencil for 3 hours…right?! Wrong. Although, “true” IQ tests, administered by trained psychologists, can easily take over one hour, there are quicker options that do not suffer much in terms of accuracy (or reliability and validity, statistically speaking).

To measure IQ, we only need exactly 12 minutes thanks to a fascinating test called the Wonderlic, a timed 50-question multiple choice test that actually has been shown by some researchers to correlate highly with scores on officially administered IQ tests. The best part about the Wonderlic is not only that you can complete it before your favorite episode of The Office finishes, but also that you can compare your score to that of some of your favorite NFL players.

To measure conscientiousness reliably, we can certainly use a normed personality test such as The Hogan Personality Inventory, which has been tested and used in thousands of organizations and research studies over the past 30+ years. But we could also use just four questions that take less than a minute in total, thanks to the clever work of a group of researchers at Michigan State who were keen to help out legions of undergrads seeking a few extra dollars in the lab by saving them a few minutes of their time. (Many basic personality questionnaires suffer from what’s called “social desirability bias,” meaning that respondents can game the test by giving the “correct” answers, but this is often addressed in research with a short scale.)

Now back to the point of curiosity laid out at the outset of this article: Does graphology (i.e., analysis of handwriting) predict job performance in any meaningful way? It turns out that analyses of one’s handwriting have been shown in some studies to correlate around 0.20 with future job performance (compared to about 0.5 for highly valid techniques like work samples). However, therein lies the problem; graphology has only been shown to have predictive power if the person is writing about a topic that they choose and are knowledgeable about. What this indicates more than how one writes being predictive is instead that what one writes can be helpful for understanding a person. In other words, I can tell very little about your personality and job performance based on the cleanliness or messiness of your handwriting. But if I see that you are knowledgeable and passionate about biology, I may be able to infer that you are intelligent and could perform well in a variety of jobs.

While it is certainly impressive that a concept as messy and uncertain as job performance can be predicted at all in such a short time, it is important to remember that although predicting 36% of job performance is good, the remaining 64% matters quite a bit as well—and that 64% may be the part that makes us human and can’t be meaningfully captured by any simple paper-based test.

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