**Link**: Data visualization

## Quantiles

In general, quantiles are the **lines that divide data into equally sized groups**.

**The median (50% quantile or 0.5 quantile)**:**The median is also a quantile**because it splits data to 50/50.**25% quantile**: It cuts the data and 25% of data points are less than it.**75% quantile**: It cuts the data and 75% of data points are less than it.

## Percentiles

Percentiles are just **quantiles that divide data into 100 equally sized groups**. *In practice, the term is more flexible*.

E.g. Even if the size is less than 100, we can still **call the 50% quantile as 50% percentile**.

## Usage of quantiles and percentiles

Both quantiles and percentiles are not limited in above examples. We can call the data point **based on its own group, such as 7% quantile/percentile**.

## quantile() in R

In R, the `quantile()`

function provides **different ways to calculate quantiles**. The difference gets smaller when the data set is larger.