When Numbers Mislead

The New York Times
Sunday Review

May 25, 2013
By Stephanie Coontz

IT'S always seductive to know where one stands in relation to the average. As an overly confident college freshman, the first time I received a below-average score on an exam was a needed wake-up call. Today, I find it encouraging to read that I exercise more than the average woman my age.

Averages are useful because many traits, behaviors and outcomes are distributed in a bell-shaped curve, with most results clustered around the middle and a much smaller group of outliers at the high and low ends. Knowing the average number of births in an area can help builders decide how many bedrooms are likely to be needed in new houses, and alert policy makers to a brewing fertility crisis.

But averages can be misleading when a distribution is heavily skewed at one end, with a small number of unrepresentative outliers pulling the average in their direction. In 2011, for example, the average income of the 7,878 households in Steubenville, Ohio, was $46,341. But if just two people, Warren Buffett and Oprah Winfrey, relocated to that city, the average household income in Steubenville would rise 62 percent overnight, to $75,263 per household.

Outliers can also pull an average down, leading social scientists to overstate the risks of particular events.

Most children of divorced parents turn out to be as well adjusted as children of married parents, but the much smaller number who lead very troubled lives can lower the average outcome for the whole group, producing exaggerated estimates of the impact of divorce.

Things get even messier in cases in which people have very different responses to life events. In these cases, the "average" response often does not in any way match the "typical" experience. There may even be three or four distinct "typical" experiences. This problem is more common than many researchers have previously realized, according to a paper to be released this week by the Council on Contemporary Families, where I am the director of research and public education.

On average, people's reactions to stressful events like divorce or bereavement indicate a sharp and long-lasting decline in personal well-being, followed by a slow and gradual recovery. And on average, married individuals report themselves happier than single or divorced ones. But in this new paper, "The Trouble With Averages," the psychologist Anthony Mancini shows that treating the average response as if it was the normal or typical outcome can lead to bad social policy and inappropriate therapeutic responses.

In the case of loss, the average is skewed by a relatively small percentage of people who exhibit substantial, persistent distress. Most people actually experience "a modest, short-lived increase in distress that subsides within a few months." When Mr. Mancini and his colleagues studied people's reaction to the loss of a spouse, they found that only 20 percent of the bereaved went through the "conventional" pattern of grieving - a sharp dip in well-being followed by a gradual return to previous levels of satisfaction. Almost 60 percent did not experience persistent sadness.

When we assume that "normal" people need "time to heal," or discourage individuals from making any decisions until a year or more after a loss, as some grief counselors do, we may be giving inappropriate advice. Such advice can cause people who feel ready to move on to wonder if they are hardhearted.

Almost 15 percent of the bereaved individuals that the researchers studied reported persistently low levels of life satisfaction after their loss. But because they measured people's well-being four years before as well as after the loss, the researchers were able to show that this was not caused by the bereavement. Rather, it was part of a chronic pattern of low life satisfaction that long preceded the loss.

Surprisingly, about 5 percent of the sample reported higher life satisfaction after their loss. They might have been in a stressful caregiving role or trapped in an unhappy marriage. Treating them as if they ought to be depressed could just make them feel guilty.

Does the fact that on average married people are happier mean that we should promote marriage?

The vast majority of people that Mr. Mancini and his colleagues studied - almost 80 percent - already reported high levels of well-being before getting married, with no significant increase afterward. More often, marriage seems to be a reward for having a high level of well-being than a route to attaining it.

A small group - 5 percent - experienced increasing well-being in the years before the marriage, then sustained that afterward. But 6 percent demonstrated a sharp decrease in well-being in the years following their marriage.

Only 10 percent found that getting married cured their unhappiness. These individuals had experienced decreasing well-being in the years before their marriage but became happier afterward.

The beneficial effect of marriage for this small group supports an earlier study by the sociologists Adrianne Frech and Kristi Williams showing that the average association of marriage with improved mental health is largely driven by the comparatively small number of individuals who are seriously depressed before getting married.

When the sociologists Sheela Kennedy and Frank Furstenberg studied marriage and divorce, they found that for people who had been in the highest-quality marriages, divorce produced very large and persistent decreases in overall happiness. But for people who had been in the lowest-quality marriages, divorce was associated with an increase in happiness. And the majority of divorced people were resilient. They did not experience large declines in happiness, and their depression levels did not differ significantly from those of people who remained in marriages of a similar quality.

Most people would agree that single motherhood is stressful. Yet consider the startling finding by Kristi Williams, Sharon Sassler and their coauthors that young, single, black and Hispanic mothers who married after their child's birth had worse midlife health than those who hadn't married by the age of 40.

I am not advocating that we give up on averages. Used cautiously, they help to analyze patterns and formulate policies. But given the variety of circumstances that exist in the messy real world, we ought to think twice before doling out one-size-fits-all advice to individuals on the basis of averages.

Stephanie Coontz teaches family studies at The Evergreen State College in Olympia, Washington, and co-chairs the Council on Contemporary Families. Her most recent book is A Strange Stirring: The Feminine Mystique and American Women at the Dawn of the 1960s (BasicBooks).

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