Precision and Accuracy

Precision: It is the measure of how close the results are to each. It can be measured with the help of variance or standard deviation of the results. It is inversely proportional to the variance and is highest when the variance is equal to zero.

Accuracy: Accuracy measures how close the result is to the true value. In case of multiple results, we take the average and compare it to the true value. Accuracy is measured as:

$$\text{Accuracy = True value - Obtained value}$$

Difference between Precision and Accuracy

The difference between precision and accuracy concerning numerical methods are as follows:

Precision	Accuracy
1. It measures how close the results are to each other.	1. It measures how close the results are to the true value.
2. It can be measured with the help of variance of the result.	2. It can be measured as the difference between true value and obtained value.
3. It is determined by the number of bits used to represent a number.	3. It is determined by precision and average value.
4. It can be improved by increasing the number of bits used to represent a number.	4. It can be improved by increasing precision, performing more iterations, taking accurate data input, using more accurate methods/models etc.

Visualization of Precision and Accuracy

In the following diagram, the filled circle at the center represents the true value. The stroked circles represent the results obtained from numerical methods.