“It seems like there is always some conflict over new performance-enhancing drugs in sports,” says Michael. “If you stop players from using one chemical compound, they just substitute another. Maybe it would be simpler if everyone just decided players can use whatever chemicals they want.”

“No way!” says Chris. “That would change the whole idea of athletic competition in a fundamental way. Using drugs is cheating. And if we stopped thinking of it as cheating, it would put pressure on all athletes to keep up by using drugs that might have unsafe side effects.”

“I don’t know,” says Michael. “Do you really think drugs like steroids make a big difference in baseball, for example? I mean, just having bigger muscles doesn’t mean you’re going to be coordinated enough to hit better.”

“Steroids might not alter your coordination,” says Kyra, “but strength obviously plays a role in baseball. If two batters are equally coordinated, the stronger one should get more home runs.”

“Can you prove that?” asks Michael. “I mean, as long as steroids aren’t allowed, players try to keep any drug use secret. That makes it hard to compare batters with steroids to batters without steroids.”

“That’s an interesting problem,” says Ms. Kahn. “Can you think of a way to find some data that might be relevant?”

Michael, Chris, and Kyra did some research and learned that Major League Baseball started testing players for steroid use in 2003. They figured that with testing, illegal steroid use might have dropped abruptly in 2003. They decided to compare the average yearly home run records in the five years before and after testing began.

Discussion Question:

What do you think these data suggest about the effect of steroids on batting? Explain your reasoning.