Parent Research 101: Cause and Effect

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Cause and effect aren't always this simple.

It's back-to-school season, which means we're all reading about how playground equipment might kill us, or why kids should never be allowed to go to school when sick, or why they should always attend school while sick, or why kindergarten is making them stupid. 

This is a great time to think about cause and effect. 

Take, for example, the oft-asserted notion that putting your child in pull-ups means it takes longer to potty train. This claim is made not just about kids who are actively potty-training, but all kids, even those who have not yet begun to train.

There is absolutely no reason that this second claim should be true. A pull-up is a diaper that pulls on instead of sticks on. Aside from being more expensive and easier to put onto a standing child, there is no major difference between a pull-up and a diaper. But because two events (wearing pull-ups and starting potty training) often occur around the same general age, they are imagined to be in a cause-and-effect relationship.

Parents who allow potty-training kids to wear pull-ups may find that the kids use them as diapers. But that does not mean that a child who is not potty-training cannot benefit from pull-ups. Why wouldn't you want to use pull-ups when you've had to use a public restroom without a changing table? The diapers cost more per unit, which is a legitimate reason to prefer tab-based diapers. But if the pull-ups fit your child better and prevent you from having to lay him on a public restroom floor, it's worth the extra 10 cents.

The diaper example is relatively trivial. If you choose not to use pull-ups because of the assumption they delay potty training, you may have to wash the clothes that came into contact with that public restroom floor. Or your bedding, after it comes into contact with a thrashing two-year-old who has outgrown your changing table. But the cost of a load of laundry versus the cost of a pull-up comes out relatively equal.

The problem is that mistaking cause and effect is not always so innocuous. In the case of vaccinations, misunderstanding of the cause-and-effect analysis has led to serious public health risks. Take, for example, Minnesota's measles outbreak, which has disproportionately affected the Somali immigrant population. Those immigrants have been encouraged to avoid vaccines by none other than Andrew Wakefield, the man whose own fraudulent research on the link between vaccines and autism (cause) led to the loss of his medical license in the U.K. (effect). 

Many others (myself included!) have discussed why the myth of vaccines and autism has such staying power in the wake of such strong contradictory evidence. There's distrust in institutions, concern for personal freedoms, and prioritization of individual health over public health. There's also, as Parks and Rec's Jeremy Jamm reminds us, "misinformation, panic, death, Jenny McCarthy."

I would argue that one of the reasons the vaccines-autism debate has such staying power is misunderstanding of cause and effect. Children receive a lot of vaccinations, and those vaccinations are usually memorable experiences for parents and kids because one or the other group is often crying by that point of the pediatrician visit. So when a few weeks or months later a parent receives an autism diagnosis, she can recall that specific moment when everyone was crying and then identify all the things that have been "wrong" since that moment. 

One of the best ways to improve your research skills is to question cause-effect relationships. The first question to ask is whether or not the "effect" actually happened. In the case of Pull-Ups, how do you know that your child is taking longer to potty train? Longer that whom, exactly? It's really hard to compare your own child's timeline to any other child's timeline because, unless you live in a country whose day cares use potty benches, kids learn to potty train at different ages. 

When you have verified that an effect has actually happened, the next question to ask is whether you can identify what caused it. If your child burns his hand, you have a pretty good sense for what burned it (the iron he just pulled off the ironing board, the stove he just figured out how to turn on, the sun that he stayed out in without sunscreen).

When cause and effect are more distanced from each other, it's much harder to determine what the cause of a particular effect was. Some cause-effect relationships are like bomb fuses. There's often a short link between cause and effect. But others are like Colin Salmon-worthy domino displays (RIP, Shakespeare!) where an effect results from a series of connected causes. 

A final question we might ask is whether or not we need to know the cause of anything in the first place. It's convenient and comforting to attribute negative effects to outside causes. But sometimes there's just not a simple answer.