Quantiles
A quantile is a percentage that splits the data into groups that contains the same number of data points. For example, the Median is a quantile, since it splits the data set in half. This can be labeled as or .
If the median value is , then we can say that the quantile value is .
- The quantile value indicates that a quarter of the points have a value less than it.
- The quantile value indicates that three quarters of the points have a value less than it.
Percentiles
On the other hand, percentiles are just quantiles that divide the data into 100 qually sized groups.
In practice the terms are more flexible. In the figure above we don’t have 100 examples in the dataset, but we call the median (or the quantile) the 50th percentile.
statistics resources: