Accuracy and precision both relate to the quality of a measure. However, the terms have separate meanings and should not be applied as an alternate for the other. The meaning of accuracy is the extent to which a given measurement agrees with the standard value for that measurement. The meaning of precision is the degree to which the correctness of a quantity is articulated. The difference between accuracy and precision is like playing a game of darts. There can have several outcomes by shooting three arrows.
If all three arrows hit the bulls’ eye, this would show accuracy and precision. If all three arrows hit the dartboard near each other but not in the bulls’ eye, which would show precise, except not accurate. However, if all three darts were to hit the same spot in the bulls eye, it would show accuracy but precise. On the contrary, if all three darts hit the dart board in different places on the board would not show accuracy or precision.
Today, society depends on the accuracy and precision of measurements for products sold by the retail industry for many reasons. One example is, medication or other pharmaceuticals need to be extremely accurate measurements because doctors rely on the accuracy when they prescribe medication, they are assuming a level of accuracy from the pill or medication otherwise a person can die from taking the wrong dose of something. Therefore, if medication is precise but not accurate that could mean anything. A pharmaceutical company can be precise in producing pills with the same dosage, but if that dosage is not accurate than it could kill someone.
Another example could be the gasoline idea, especially considering gas prices right now. If someone is advertising $3.29/gallon but their pump is charging that much for every 4/5 of a gallon, their pump is precise because it keeps charging the same for everyone, but it is not accurate.
Another idea is baking. Say someone is making a ton of cookies for a fundraiser or something. That person starts making batch after batch of cookies, but it is not until the 6th batch that he or she realizes that he or she has been using the tablespoon to measure the salt instead of the teaspoon. The cookies will taste the same, but they are not going to be very good because they will be too salty.
The three types of measurements used in life to compare and contrast the accuracy and precision are the bathroom scale, a wristwatch, and a yardstick. The bathroom scale that reads to a half pound: The readings may be accurate, which could be seen if a person weighs him or herself on a doctor's office scale, and get a similar reading on the two scales. However, the bathroom scale is not very precise; it only reads to a half pound, which could up or down by an entire half of pound. A wristwatch that can keep time to the hundredth of a second; in other words, it is capable of taking very precise measurements of time.
The watch is set an hour ahead of the time zone it is in. Although the watch is very precise at measuring time, it is not very accurate and close to the right time. A yardstick used to measure the length of a fence: someone bought a piece of fence at the hardware store and the packaging said it stood two-feet tall. When that person took it home and measured the fence with a yardstick, found it was two-feet tall.
He or she repeated the measurements a few times, and got two-feet or very close to two-feet each time. In this case, were both precise in getting close to the same measure each time, and accurate in getting the same measure as the packaging said the fence was.
In conclusion, accuracy is similar to precision, yet they are quite different. Measuring devices or techniques can easily be inaccurate and lead to false measurements, and no matter how accurate a device may be, there is still a tolerance for error. No measurement is perfect. Precision depends on the unit used to obtain a measure, the smaller the unit, the more precise the measure.