Wednesday marks the 100th day of the Obama presidency, and a great debate rages over how he is doing.

The trouble with this debate is, however, that no one can even agree on the terms.

Do we measure the economy? And if so, what aspect? Jobs? Lending? The stock market?

Or should foreign affairs rank higher? And if so? What aspect? Iraq? Afghanistan? Venezuela?

And, by the way, is it even useful to measure after 100 days? Why not 97? Or 197?

This debate underlines the beauty and value of sport. No matter what happens in the game, you can measure the final score. You can’t debate it. You can debate the strategy, and complain about the officiating. But the verdict stands.

For instance, on this date exactly 100 years ago, the New York Giants beat Boston 5-3 in a National League baseball game. Without knowing anything else about the game, you can say that the Giants were more successful than Boston that day.

One job of a coach is to develop a way to measure performance and progress, and to remove opinion and debate. What do you measure? In what way? How often?

Statistician Bill James changed the way baseball clubs view their players. For a century, the baseball establishment revered batting average as the measure of a batter’s value. Then along came James, who argued that on-base percentage is a much better indicator. Now everyone — fans, players, agents, teams —  pay lots of attention to on-base percentage. It seems to be the right thing to measure. 

Like Bill James, you can invent your own metrics.

Comedian Jerry Seinfeld knew that if he spent time writing jokes every day, he would write some very good ones. So he focused on writing every day. He measured his success NOT by the quality of the jokes he wrote, but by whether or not he actually sat down and did the work.

So in your gym or on your field, are you measuring what is going on? Are you measuring the right thing? In the right way?

It will make all the difference.