Variables Accuracy Precision

While studying chemistry, we will come across many quantities

Some of these quantities are fixed. They do not change. These quantities are called constants

On the other hand, some quantities do not have a fixed value. They can change. They are called variables

Variables are further of two types- Discrete and Continuous Example

A discrete variable is a variable can only have a finite number of possible values.

For eg: The grade obtained in an exam will be a discrete variable. There is a finite no. of possible grades you can get

Whereas a continuous variable is a variable that has an infinite number of possible values

Weight is an continuous variable. There is no finite no. of possible weights you can have. You can have any possible weight

The value of both types of variables is found by doing appropriate measurements

However these measurements can also generate errors in the true value

So when we measure a variable, the error is kept in check by 2 things- accuracy and precision

Accuracy is how close the measured value is to the actual or standard value (truth value)

The closer a value is to the standard value, the more accurate it is.

So first weight is more accurate because (100-99.89)=0.11 is less than (100-98.89)= 1.11

Apart from accuracy, precision is also needed to tell how good our measurements are

Precision is the degree of closeness of two or more measurements. The closer the data, the better it is.

Values should always be close to each other in experiments, if not the exact same every time.

High accuracy and precision are needed to get good estimates of variables

We can see the usefulness of high accuracy and precision from a game of basketball

Consider a basketball team which is shooting in different places and doesn’t score once

They have low accuracy - because the ball doesn’t hit the correct target- here, the basket

They have low precision- because the throws are not close to each other and not consistent

The team begins working harder and hitting the rim consistently but not scoring.

They still had low accuracy because the ball yet doesn’t hit the correct target- here, the basket.

They now have high precision- because the throws are close to each other and are consistent.

With some more hard work, the team began scoring in all the shots they attempted

They now have high accuracy because the ball does hit the correct target- here, the basket.

They also have high precision- because the throws are close to each other and are consistent.

So with high accuracy, they scored when they throwed the ball With high precision, they scored on every throw


Variables are values which may change and constants are anything which do not change

Variables are either discrete- finite values or continuous- having a range of maxima and minima

Accuracy is the measure of correctness of the measured value and the standard value

Precision is the degree by which we get the same (or closest) value when we repeat an experiment multiple times

As seen in the basketball example, outcomes may have different values for precision and accuracy individually.

The End