S1, Ep 8: Dartboards and Accuracy vs. Precision

Caroline Christian, Ph.D.

What is the difference between accuracy and precision? Accuracy is how close your measurement is to an accepted or true value. For example, you need to weigh a 5-pound weight, and you weigh it on three different scales. The first tells you it is 4.9 pounds, the second 7.60 pounds, and the third 10 pounds, obviously the scale that told you it is 4.9 pounds is the most accurate. Precision is something completely different. Precision is how close the repeated measurements are to each other. For our example with the three different scales, these measurements are not precise. They usually represent accuracy and precision in chemistry textbooks with dartboards. If you throw three darts and they all land in the middle of the board, then you are accurate and precise. If you throw three darts and they all land close to each other but not near the middle, then you are precise but not accurate. If you throw three darts and they land all over the board, then you are neither precise nor accurate. Here is a picture of a dartboard, if you need a visual! Which of the darts is accurate? Are any of the darts precise?

03/02/2018

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