STATS ARTICLES 2010
To cohabit or not to cohabit?
Rebecca Goldin Ph.D and Cindy Merrick, October 22, 2010
Thatís the question behind a new study that confused journalists.
Marriage is not immune to the perennial confusion among journalists between cause and correlation. News organizations recently weighed in on whether living together before marriage makes the wedding bells ring untrue. In other words, does premarital cohabitation increase the chance of the marriage breaking up?
A recent report from the Centers for Disease Control (CDC) has provoked an assortment of conflicting interpretations. USA Today, for instance, ran with the headline: “Cohabiting Has Little Effect On Marriage Success,” while The New York Times took the opposite vantage point, reporting that it doesn’t help a marriage to live together first, and that “the likelihood that a marriage would last for a decade or more decreased by six percentage points if the couple had cohabited first, the study found.” The Arlington Catholic Herald claimed the CDC’s report has “proclaimed doomsday for couples who cohabitate prior to their big day.”
Could all of these stories have been written from the same set of statistics?
The much-discussed report, “Marriage and Cohabitation in the United States,” was published in February 2010 by the CDC’s National Center for Health Statistics, and is based on the National Survey of Family Growth. It defines the word “cohabited” as having “lived together with a sexual partner of the opposite sex.” Despite the breadth of demographic perspectives on marriage, cohabitation and divorce given by the report’s data, the probabilities that cohabitation prior to marriage is followed by marriage disruption (divorce and separation are grouped together) in less than ten years that have gotten the most media attention.
The report states its objective as “describing the marital and cohabiting relationships of men and women aged 15-44,” and the statistics on marriage disruption are from a nationally representative sample of over 12,000 men and women, ages 15-44, provide a picture of marriage and previous cohabitation across social, economic, and racial lines.
Inevitably, it is from this plethora of data that evidence for completely contradictory views can be cherry-picked. For example, among the whole sample, the probability for a woman of a “disruption” within 10 years of marriage is reported as 36 percent. Broken down by prior cohabitation (or not), the probability rises to 40 percent for those who did cohabit, and drops to 34 percent for those who did not. However, the authors make clear that, for these numbers, “the difference was not statistically significant.” (p.13) In other words, when margin of error is taken into account, it cannot be said with confidence that there is a difference in the true value (in the population as a whole, rather than in the sample), let alone enough to warrant a proclamation of doomsday.
If the media focused on findings that weren’t statistically significant, they largely ignored the demographics findings that were, such as ethnicity, whether either spouse had children prior to marriage, or whether both spouses share the same ethnicity.
For example, for a marriage in which the husband is of different racial origin from his wife, there is a 46 percent probability that the marriage will not be intact by their tenth anniversary. Hispanic marriages have a 32 percent probability of dissolving within ten years, but black or African American marriages have a 49 percent probability. There is a 66 percent probability that a marriage in which no children are born at all will not survive for ten years. Moreover, if a couple is engaged when they begin to live together, their subsequent marriage is as likely to survive the ten-year mark as any other marriage (p.32).
Comparing the new data to similar data from 1987-88, Pamela Smock at the University of Michigan’s Institute for Social Research, concluded that these recent data indicate that living together is no longer by itself a risk factor for a marriage ending in divorce. Smock observed that “on the basis of these [CDC’s] numbers, there is not a negative effect of cohabitation on marriages, plain and simple.”
William Mosher, co-author of the CDC report, gave a moremeasured interpretation regarding cohabitation, saying that “the differences are there, but are not huge.” He pointed out that there are many types of cohabitors, and that finally the nationwide data reflect that. In other words, both people with high risk for divorce and people with low risk from divorce cohabit before marriage. As Philip Cohen wrote in the Huffington Post, “Striking as its presence has become on the demographic palette, cohabitation has been hard to study, because although it precedes more marriages, it's a state most people don't stay in for long, and they get into for very different reasons, in different contexts.”
Additionally, USA Today seemed to misunderstand percentages, reporting that “Of those married 10 or more years, 60% of women and 62% of men had ever cohabited; 61% of women and 63% of men had cohabited only with the one they married. Meanwhile, 66% of women and 69% of men married 10 years had never cohabited (USA Today,3/2/2010).
These numbers don’t make sense. Of women married ten or more years, how can 60% claim to have cohabited, while 66% claim they have not? What it meant to report was that of women who had cohabited prior to marriage, the probability that they would still be married after ten years is 60 percent, while those who did not cohabit have a probability of 66 percent of being married ten years later.
In sum, the CDC report demonstrates nothing less than the complexity of social and economic factors involved in the relative strengths of any union. Many of these demographics are more than statistically significant, but causally relating the notions of marriage success and failure to any single variable, such as prior cohabitation, is a naïve evaluation of these statistics.