Accuracy VS Precision: Difference, Example

Accuracy and Precision

What is Accuracy?

Accuracy tells how close a particular measurement is to the correct value.

Example: Suppose you are measuring the temperature of a body with a thermometer. Accuracy defines how close is the reading of thermometer to the actual temperature

What is Precision?

Precision is the consistency of a repeated measurement.

Same Example: If you take multiple temperature readings one by one, are the readings consistent ?. The more consistent the readings are, the more precise the thermometer measurement is.

Accuracy VS Precision EXAMPLE

Suppose the original weight of a body = 50 kg.

Now we are using a weighing machine to calculate the weight of this body, and try to find about the accuracy and precision of the weighing machine. We take 5 measurements one by one

Scenario 1 readings: 50, 50, 50, 50, 50  

Readings = Actual temperature —–> Machine is Accurate

All Readings show same value ——-> Machine in Precise 

Scenario 2 readings: 46, 46, 46, 46, 45.5

Readings Not Equal to Actual temperature —–> Machine is In-Accurate

All Readings show almost same value (though incorrect) ——-> Machine in Precise 

Scenario 3 readings: 49.5, 50, 50.5, 50, 49

Readings almost equal to Actual temperature —–> Machine is Accurate

All Readings show different values (though close to original) ——-> Machine in Imprecise

Scenario 4 readings: 40, 53, 47.5, 50, 48

Readings Not equal to Actual temperature —–> Machine is In-Accurate

All Readings show different values ——-> Machine in Imprecise