I have some bad news that, I hope, will turn out to be good news. Psychological studies are not about you. They make few if any predictions about how you should live your life, how to tell if you’re an introvert, or anything else about you as an individual.

I’m not trying to pull a Carly Simon on readers, most of whom probably understand this already. My point is that a consumer of psychology, as it’s offered up in blogs, newspapers, and popular books, could be more than forgiven for coming away with the conclusion that our studies are about them. This is because oftentimes, popular psychology is explicitly pitched this way: as information about you—the individual reader—how your mind works, and even what you should do to make it work better.

Take a recent blog post titled “10 Simple Things You Can Do Today That Will Make You Happier, Backed By Science.” The author makes some perfectly good suggestions for increasing well-being: get some exercise, spend time with family, act generously, and so forth. What’s more, she cites some great research. For instance, the study she mentions by Lara Aknin and colleagues, on positive “feedback loops” between generosity and happiness, is part of a robust and fascinating research program.

Perfectly good suggestions paired with great research sounds like a recipe for informative and useful science writing, so why am I so grumpy about it? Because when put together in the wrong way, these ingredients can mislead people about psychology and its purpose, or worse, produce personal disappointment.

A useful way to describe this tension is by way of analogy to baseball. Batting average, the percentage of times that a player gets a hit for each “at bat” (or trip to the plate) is maybe the most famous measure of baseball performance. Players covet averages of .300 (30% hits) or above, and players batting above .300 make much more money than those below .300. As such, two batters with averages of .320 and .290 are worlds apart. Crucially, though, these two batters would be virtually indistinguishable if you only saw each of them at the plate once. This is because a .030 difference translates to a difference of about 20 hits per season, or only one extra hit for every 30 or so at bats.

Like batting averages, psychological studies tell us about behavior over lots of cases, but say little about any one case. Photo credit: AJW on Tour via Flickr

Findings from psychological studies are a bit like batting averages. Except—and this is critical—you’re not the batter. You’re the at bat. This is because psychology is a science of populations. A typical study might include 200 people, dividing them into groups (say, people told to act generously versus those told to act selfishly), and demonstrate a statistically significant edge in happiness for one over the other. Like a batting average, though, even strong differences across groups tell us virtually nothing about how generosity or selfishness would affect the happiness of any one person.

Suggesting the opposite—that science provides readers with magic bullets that will change their lives today—is harmful in at least two ways. First, it misrepresents psychology’s goals. Experimental psychologists do not, by and large, claim their studies reveal much about any one individual. Suggesting that we do can produce a false sense that psychology is over-promising and under-delivering. Second, this type of writing can make people feel like outliers when they are not. If a reader believes science has proven that generosity will make them happy, and it doesn’t, this person might wrongly feel like a counter-normative Grinch.

The good news is that this type of writing is totally unnecessary, because averages provide just as powerful (or more powerful) a message when divorced from any one person. Knowing players’ batting average—though it doesn’t tell you about any one at bat—is crucial for predicting how a team will perform over a season. Similarly, psychological studies, without telling us about any one person, can tell us about how changes in behavior (again, think generosity) might affect the well-being of whole populations. Such insights can inform policy on a broad scale; in fact, the newly created White House Social and Behavioral Science Team will use psychology in just this way. Most sciences—including psychology—are much better suited to these broad applications than to telling any one person about their life. That said, it probably wouldn’t hurt to get some exercise anyways.