Percentile

More detailed mathematics

Various mathematical tasks can instill fear in anyone. This often stems from one’s school days, when the ‘queen of sciences’ forced us to focus intensely and be vigilant. There are many mathematical topics that you have probably not covered in class or you have only heard about them in passing – one of them may be the percentile.

WHAT EXACTLY IS A PERCENTILE?
In practice, the abbreviated form ‘centile’ is also used. The percentile is a statistical category so to better explain this issue, it is worth using the method of deduction.

The median is the value which shows the middle or half of a given set, while the quartile shows 1/4 – a quarter of the set. Going further, the percentile will correspond to 1/100. This can be illustrated as follows:
Median (second quartile) = 1/2
Quartile (first quartile) = 1/4
Decile = 1/10
Percentile = 1/100
This means that the percentile is equal to 1%.

EXAMPLE OF USING A PERCENTILE
Percentiles are mainly used in diagnostics – especially in paediatric diagnostics to classify a particular result in relation to the rest of the subjects. A percentile grid is used to help determine the percentage of a child's measurements (e.g., height or weight).

If a child is 163cm tall, the doctor will assign him a number of percentiles on this basis. When s/he gets 48 percentiles, it means that 48% of the examined persons have a smaller or the same result.

Thanks to the percentiles, it is known how the child develops in comparison with the rest of his/her peers. This helps to determine whether growth is normal or stunted.

Statistics - Topics