The research led by John Cacioppo, a University of Chicago psychology professor who also works as a paid adviser to the online dating site eHarmony, estimated that more than a third of couples who married between 2005 and 2012 met online.
The study analyzed the online survey responses of 19,131 Americans who said they had been married once between 2005 and 2012 and were not engaged to anyone else. The survey was conducted by the polling firm Harris Decima and commissioned by eHarmony.
A total of 191,329 people responded initially to the survey when invited to do so in June 2012, but many were ineligible or fell into categories that were too small to produce good data, such as people who had married three times between 2005 and 2012.
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Among the once-married respondents, about 45 per cent had met through an online dating site. However, once the data was adjusted to take into account the difference in demographics between the sample and the general population, that translated to more than a third.
Those who met online tended to be older, more likely to be employed, and higher earners than those who met offline. Cacioppo said the finding that most surprised him was that "dramatic shift" in how people are meeting a spouse since the advent of the internet.
The data showed 5.96 per cent of those who had met online had divorced by the time they took the survey in June 2012, compared with 7.67 per cent of those who had met in "real life" venues such as school, church or a bar.
Respondents were also asked questions about their happiness with their marriage and the degree of their affection, communication and love for each other in order to generate a "marital satisfaction score." The average score was 5.64 for those who met online and 5.48 for those who met offline.
"We tested whether the difference was due to differences in marital duration, and it was not," Cacioppo told CBCNews.ca in an email.
"That is, even when you compare online and offline marriages of equal duration, those that began online were associated with slightly but significantly higher satisfaction and lower marital breakups."
The results were published this week in the Proceedings of the National Academy of Sciences.
Cacioppo and his colleagues did not determine why those who met online appeared to have happier and more stable relationships, but their analysis showed that the differences between those who met online and offline persisted even when the study accounted for the year of marriage, sex, age, educational background, household income, ethnicity, religious affiliation and employment status of the respondents.
The authors of the study suggested that those who have met online may differ on average from those who met offline in personality, or that they might be more motivated to form a long-term relationship. They said the larger pool of potential spouses accessible online may also play a role.
The study also suggested that not all online and offline meeting places were equal. Among online meeting places, online communities and chat rooms generated lower marital satisfaction scores, averaging 5.29 and 5.42 respectively, while social networks and multiplayer games generated the highest marital satisfaction scores, at 5.72 each.
Among offline meeting places, growing up together (5.67) and meeting at school (5.59) generated far higher satisfaction scores than blind dates (5.31), work (5.38) and bars or clubs (5.39).