The Urban Legend of the 50% Divorce Rate
Most of us have heard the often repeated statement that 50% of all marriages end up in divorce. This “fact” gets passed from one media “source” to another without anyone ever checking its original source. So we decided to check with the final authority on all things demographic: The Unite States Census Bureau.
Typical of statements often repeated in the media, the 50% number is an oversimplification that does not begin to tell the important story about divorce rates. There are much more interesting figures that tell us how the divorce rate has changed over the decades and suggest the reasons for their changes. But first, to understand the issues around divorce rates we need to answer this question:
Just What is a Divorce Rate?
What does it mean to say that some percent of marriages “end up” in divorce?
People stay married for many decades. Some get divorced at one year, five years, fifteen years or even sixty years after the marriage. And some die married. Therefore, we only know the rate at which marriages end up in divorce for people who married far back enough in the past for all of them to have already died.
But we can also start with a more recent cohort of people who married on the same year and estimate the divorce rate of the remaining marriages on the last available year of their data. The more recent the cohort of marriages, the longer and less reliable is the estimated period.
Or we can state divorce rates as of a given wedding anniversary, such as “35% by the 25th anniversary”. This allows us to compare divorce rates between people who married on different years by the same standard.
A divorce rate alone, without:
- stating the year of the marriages,
- qualifying it by the anniversary when the divorce rate was calculated and
- mentioning whether it is an actual or estimated rate
is a meaningless number
Is the Divorce Rate Rising or Falling?
It would be foolish to expect that divorce rates have been at the same 50% for many decades. Few things having to do with human behavior stays the same for very long. So we need to do our best to understand whether the divorce rate has been rising or falling during the last few decades.
The following article published by the Census Bureau sheds some light on the direction of the divorce rates:
Rose M. Kreider and Renee Ellis, “Number, Timing, and Duration of Marriages and Divorces: 2009, Household Economic Studies, May 2011”, Current Population Reports.
The data for this Census Bureau article was based on a survey of over 39,000 households given in 2009 to 55,597 adults that were married at some time in their lives. What follows summarizes some important facts from this article:
At the 35th anniversary, the survival rate of marriages fell form 62.10% for the cohort of men married between 1960 and 64, to 57.90% for the 1965-69 cohort. At the 25th anniversary, those survival rates fell from 66.90% for the 1960-64 cohort to only 54.40% fort he 1975-79 cohort. There was also a 離婚 drop in the 10th anniversary survival rates of 10 percentage points between the same two cohorts (which is the same as a rise of 10 percentage points in divorce rates).
After 1974, the marriage survival rates are too close together for the cohort-to-cohort changes to be significant. But, for men, the tenth anniversary survival rate gradually rose from the low of 73.40% for the 1975-79 cohort to 77.30% for the 1990-94 cohort.
In general, what we know from this study is that the men’s marriage survival rates, of the 10th to 25th anniversaries plunged by about 12 percentage points between the 1960-64 and the 1975-79 cohorts. Then their survival rate at the 10th anniversary rose by about four percentage points between the 1975-79 and the 1990-94 cohort.
The women’s marriage survival rates are generally lower and they are not as far apart between cohorts. But they tell the same story about when they fell and when they later partially recovered.
If you think about it, something looks wrong with the data when the marriage survival rates of men and women are different. As far as we know there were no same-sex marriages, polygamy or polyandry in the Unites States before the year 2009, so all marriages were of one man to one woman. When they get divorced, both marriage partners count as divorced on the same year. Therefore, if a study were to follow through their lives a sample of couples who married on the same year, the marriage survival rates (and the divorce rates) must be the same for husbands and wives on each year after the marriage.
But such a study would be very long and expensive, which is why this study was based on interviews with 55,597 people in over 39,000 households in 2009. Since divorced people are very unlikely to be living in the same households, the former husbands of the divorced women interviewed (and the former wives of the divorced men) were very unlikely to be in the sample. Consequently, the divorce dates and total divorce rates of the women are unrelated to those of the men. This is why the men’s and women’s divorce rates differ.