Why is precision not the same as accuracy?

Precision is not the same as accuracy because precision refers to consistency of results, while accuracy refers to closeness to the true value.

In the realm of physics, and indeed in all scientific disciplines, precision and accuracy are two distinct concepts that are often misunderstood and used interchangeably. However, they represent different aspects of measurement and have unique implications for the interpretation of data.

Accuracy is a measure of how close a measurement is to the true or accepted value. For instance, if you were to measure the length of a standard A4 sheet of paper, which is known to be 297mm, an accurate measurement would be one that is very close to this value. If your measurement is 296mm or 298mm, it would be considered accurate because it is close to the true value. Accuracy is about hitting the bullseye, getting as close as possible to the true value.

On the other hand, precision is about the consistency or repeatability of measurements. If you were to measure the same A4 sheet of paper multiple times and consistently get a measurement of 300mm, your measurements would be considered precise. They are not close to the true value (and therefore not accurate), but they are consistent. Precision is about hitting the same spot over and over again, even if it's not the bullseye.

In an ideal world, scientific measurements should be both accurate and precise. However, various factors such as the quality of the measuring instrument, the method of measurement, and human error can affect both accuracy and precision. It's important to understand the difference between these two concepts, as they can significantly impact the interpretation of data and the conclusions drawn from it. For example, a series of precise but inaccurate measurements can lead to a false conclusion, while a series of accurate but imprecise measurements may indicate a need for improved measurement techniques or tools.