Each night, in the United States, more than 50 million children eat dinner without their fathers. Given this grim statistic, it seems appropriate to wonder what difference a father makes anyway.

Or, put differently, does dining with Dad matter, or is a father at the dinner table like a kidney or a lung — nice to have but not essential for living?

We might start by looking at the scientific studies that measure a child’s well-being by his parents’ presence at the dinner table.

The most famous — the one cited repeatedly by newspaper columnists and talk show hosts — is a report by the National Centre on Addiction and Substance Abuse at Columbia University that concludes that “the more often teens have dinner with their families, the less likely they are to smoke, drink or use drugs”.

A spokesman on the centre's website declares: “Parents, there’s something you can do to protect your kids from drugs and alcohol. Combine ground beef with egg, tomato sauce, breadcrumbs and spices. Bake in an oven-safe pan at 350 for 50 minutes. Serve hot.”

Other studies, for example one conducted by researchers at Harvard Medical School, seem to suggest that children who eat dinner with their families are less likely to be overweight.

So Dad matters, right?

Wrong. For one thing, neither of these studies specifically examined the importance of a father’s presence at the table.

While it may be true that families that do not sit down to eat together have a higher incidence of children who abuse drugs or are overweight, this tells us nothing about families where Mom is the only parent in the home.

More important, the studies demonstrate a correlation, not a cause. They prove only that two things often go together, not that one causes the other.

They have about as much significance as a study demonstrating that everyone who drank water between 1800 and 1820 is dead, and therefore, drinking water must kill you.

There are, in fact, stronger correlations that get less attention in the substance abuse centre's study, like age.

Not surprisingly, families with older children tend to have more incidences of drug use, and these are the same children who are less likely to be home at dinner. So, too, according to the centre's own research, do families in which youngsters watch R-rated movies and have sexually active friends.

The centre's study also fails to take into account a family’s socioeconomic status, or whether other members of the family have a history of drug use, factors that are much more closely linked to substance abuse than eating together.

The Harvard study acknowledges that “there is the possibility that there is truly no association between family dinner frequency and overweight incidence”.

Yet the studies continue to get a lot of press because they attempt to quantify something that is inherently unquantifiable. Parents want concrete advice, and there is always someone happy to oblige.

But parenting cannot be evaluated by sheer data crunching, just as intellectual prowess cannot be measured by the number of books in a home. The traits that make a good parent are far more complex than can be captured in a simple cross-sectional study.

By calculating family well-being by the number of shared meals, these studies give us a false sense of control.

They also, perversely, encourage arguments on the other side. If, in fact, it turns out that being home for dinner makes no statistical difference in children’s lives, if staying married to their mother confers no admission advantage at Harvard, then a father might be forgiven for his absence.

In advocating for the family dinner as if it were exercise or prescription medication, we lose sight of the reasons we come to the table in the first place.

The real question is not whether Dad matters — he may or may not — but what has Dad lost? In missing the family dinner, we fathers are missing a large portion of our children’s lives, the part they are living right now.

Without dinner as a touchstone, it is so much easier to let the rest of the day slip away as well. How soon before our children are grown and out of the house, the family table a forgotten memory? How soon before they do not miss us at all? They may recover just fine, but we may not.

Here is the reason, then, to come to the table: Your daughter, 7 years old, two hands grasping a glass as she raises it to her lips. “Daddy,” she asks, “Why is milk white?” The answer is just an arm’s length away.