Are You Accurate or Precise?


I’m not a huge sports fan but I have heard a few sporting commentaries. On the eve of the beginning of the 2011 Australian Football League season where the media spend at least 25 weeks using as many synonyms to describe the ability of footballers to kick a goal accurately. Within the first match there will be an abuse of the terms accuracy and precision used interchangeably as if they mean the same thing. They do not mean the same thing.

Accuracy and Precision, Source: Wikimedia Commons

Accuracy is how close you are to the true value. In football, this means how close a footballer is to kicking and scoring a goal successfully. Let’s assume that a footballer is having a terrific match and he manages to kick a lot of goals sending fans into spontaneous celebration and the commentator marvelling at the sporting ability.

The more often the footballer repeats the same feat of kicking a goal successfully, the higher the precision of his kick and this has nothing to do with accuracy. Assuming that the opposing team’s player for kicking the goal is missing by kicking consistently to the right of the goal posts. His precision is high as he is kicking into the same area repeatedly much to his frustration and to the disappointment of supporters. The accuracy of the footballer however, is much to be desired, as he isn’t close to the goal, the reference value.

In chemistry and indeed all sciences, the distinction of accuracy and precision is an important one. It becomes important when measuring values with instrumentation. The goal is to be accurate because you want to obtain the value as close to the real value and to be able to do this precisely every time.

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4 Comments

Filed under chemistry365, Science

4 responses to “Are You Accurate or Precise?

  1. Margaret

    So… Accuracy = validity, and precision = reliability?

    Thanks for the distinction! I truly had no idea, but I’m assuming this is because I favour flighty different terms to describe these aspects of instruments?

    • I don’t see why that comparison would be incorrect. It does seem to fit the definitions in statistics. Accuracy is like validity in that it isn’t accepted unless it can be shown that the result is able to be obtained repeatedly. Otherwise it could be a fluke.

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