If you want to be successful in the workplace, marry the right person. That's what researchers at Washington University in St. Louis suggest, at least, in a study published last year by the Association for Psychological Science.

How partners can influence career success

"You marry your spouse 'for better, for worse' and 'for richer, for poorer,' but does your choice of partner make you richer or poorer?" the researchers asked. Well, it turns out that it can. By analyzing the personality traits of spouses for more than 4,000 participants, they determined that the level of conscientiousness—diligence or dedication—of a given partner can predict future job satisfaction, income, and the likelihood of promotions.

"Our study shows that it is not only your own personality that influences the experiences that lead to greater occupational success, but that your spouse’s personality matters too," Joshua Jackson, the lead author of the study, said.

"The experiences responsible for this association are not likely isolated events where the spouse convinces you to ask for a raise or promotion. Instead, a spouse’s personality influences many daily factors that sum up and accumulate across time to afford one the many actions necessary to receive a promotion or a raise."

What this study found

Using a research method known as Saucier's mini-markers, the researchers looked at data collected from self-administered tests—which asked participants to rate themselves on a scale of 1 to 5 for traits such as extroversion, agreeableness, conscientiousness, neuroticism, and openness—in an effort to measure personalities. Only one of the five (conscientiousness) proved relevant in the context of workplace success.

"Workers who scored highest on measures of occupational success tended to have a spouse with a personality that scored high for conscientiousness, and this was true whether or not both spouses worked and regardless of whether the working spouse was male or female," the study concluded.

It works both ways: If you marry a conscientious person, it can have a positive influence on your career, and if you're a conscientious married person, you can help boost your own household income, too.

One of the lead investigators of the study, graduate student Brittany Solomon, quantified the study. She said that conscientious couples earn an average of $4,000 more than those married to apathetic partners. The more conscientious the spouse, the more money you can make together.

How the study was conducted

The reason for this trend, according to Jackson, is two-fold. For one, partners often mimic the traits of each other, so if one is industrious and effective, it stands to reason that the other will adopt those same personality characteristics over time; secondly, when you have an industrious and effective spouse, that person also tends to be the one to take care of household chores, allowing the other partner to pursue career-orientated objectives.

This is not the first time that researchers have considered the effect one's spouse might have on the success of their partner. Earlier studies have found that "positive" (i.e. healthy) relationships lend to higher levels of productivity in the workplace. It makes sense, of course, because unhealthy relationships, rife with disputes and stress, would reasonably detract from the time one spent on his or her work.

Other ways couples can be successful

And if you don't have a conscientious spouse, however, you can always just have more sex. That would lead to higher levels of success in the workplace, too, according to a study conducted by researchers at the Lord Ashcroft International Business School at Anglia Ruskin University.

The study's lead researcher, Dr. Nick Drydakis, explained that "since good health, mental health, and well-being are closely related to the economist's notion of productive output, and these characteristic are correlated with sexual activity, we may expect/hypothesize that sexual activity is also a well-being indicator related to higher wages."