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.