Accuracy and Precision are two important terms in measurement that are often used interchangeably but they have different meanings. Accuracy refers to how close a measured value is to the true value of what is being measured, whilst Precision refers to how close the measured values are to each other.

Accuracy

Accuracy is a measure of how close a measured value is to the true value. It is the degree of closeness of a measurement to the true or accepted value of the quantity being measured.

For instance, if you are measuring the length of a rod that is supposed to be 10 cm long and you measure it to be 9.8 cm, then you have an accuracy error of 0.2 cm. This means your measurement is not very accurate because it deviates from the true value.

Precision

Precision refers to how close the measured values are to each other, regardless of whether they are close to the true value or not. It is the degree to which repeated measurements under the same conditions show the same results.

For instance, if you are measuring the length of the same rod 10 times and you get results of 9.8 cm, 9.7 cm, 9.9 cm, 9.8 cm, 9.8 cm, 9.9 cm, 9.7 cm, 9.8 cm, 9.7 cm, and 9.9 cm, then you have a precision error of about ± 0.1 cm. This means that your measurements are precise, but they may not be accurate since they are not close to the true value of 10 cm.

Accuracy vs Precision

Accuracy and precision are both important in measurements. A measurement can be accurate but not precise, or precise but not accurate. To achieve a good measurement, you need to have both accuracy and precision.

- Accuracy is how close a measured value is to the true value.
- Precision is how close the measured values are to each other, regardless of whether they are close to the true value or not.

To summarize, accuracy is all about getting the right answer, while precision is about getting consistent results.