Accuracy and precision

The accuracy is the closeness of a measure to the actual value , while precision is the degree of closeness of the values of several measurements at one point. These differences are critical in metrology, science, and engineering.

In this sense, accuracy and precision acquire different meanings when referring to measurement results, be they quantitative or qualitative.

Both are independent of each other. Thus, the results in the values ​​of a measurement can be precise and not exact (and vice versa). If we take the throwing of darts as an example, if all the darts are concentrated in a small area of ​​the board, but far from the target, it is said that the shots were accurate, but lacked accuracy.

AccuracyPrecision
DefinitionIt is the closeness of the value of one or more independent measurements to a true value.It is the closeness of two or more values ​​of several measurements to each other.
DeterminationThe closer a measurement is to the true value, the smaller the error and the more accurate it is.There is more precision the closer the values ​​of different measurements are.
KeywordReal value.Repeatability
ExampleA person measures his height with a tape measure and gets 1.70 m. When she goes to the doctor, he measures her again with a special meter and the result is 1.70 m. This means that the measurement made with the tape measure was accurate.A footballer always shoots free throws on the right side of the goal. This means that your pitches are accurate.

What is accuracy?

Accuracy indicates the degree of closeness or proximity between a measured value, or a series of observed values, with the real value of something. Thus, the accuracy increases the closer a measurement of an object is to the actual measurement of that object.

In the same way, accuracy is related to how close you are to a certain target or reference point .

Accuracy depends on the calibration of the measuring instruments. The better they are calibrated, the less is the margin of error and the more accurate is the instrument.

Examples of accuracy

If a person practices target shooting and hits the center of the target, this person has shot accurately.

In a classroom there are 28 people sitting and 5 standing. The teacher asks if anyone can guess how many people are in the room with the naked eye. A student takes a look and states that there are 27 people sitting and 5 standing. In this case, the student’s observation has been quite accurate.

What is precision?

The term precision is often used synonymously with accuracy in everyday life. However, precision refers to the degree of proximity or closeness of the results of different measurements to each other , while accuracy is the closeness of the value of a measurement to the real value of what is measured.

An important aspect of accuracy has to do with repeatability . That is, how much a series of measurements or actions are repeated, as long as similar instruments are used, the same is measured and under the same conditions.

For example, if different measurements of an instrument give similar results on the same element, it can be said that said instrument gives precise measurements, regardless of whether they are exact.

This means that the results obtained when making the measurements are more dense in a specific area, being able to distinguish a pattern or truth. The more concentrated the results, the greater the degree of precision.

On the contrary, if the results of a series of measurements made (under the same conditions) by an instrument are dispersed among themselves or are very different, it can be said that said instrument is imprecise .

Examples of precision

During a soccer game, a striker kicks the ball into the opponent’s goal 7 times, of which 6 of them end up hitting the left post and another passes near the same post, without scoring a score for his team. This forward is quite precise, since he always shoots at the same point, but he is also very inaccurate, because he cannot score.

Another example of precision if a person weighs himself for four days in the morning on a scale and the result is 70 kg, 69.5 kg, 70.2 kg and 69.75 kg. In this case, the measurement is quite accurate, as the results of each individual measurement are quite similar.

On the other hand, if the person in the previous example weighs 73 kg, it is likely that the scale has a problem and therefore its results are inaccurate, even if they are accurate.

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