Annual rainfall in Samaru
Drag the red horizontal line to read the cumulative distribution function the opposite way — from the cumulative proportion to a value — the corresponding percentile.
Discuss the fact that the proportions are only approximate. For example, this data set has n=56 values so there is no value for which exactly 37% of the data are lower.
Also mention that we have not uniquely defined percentiles. For example, if there are an even number of values, 50% are below any value between the middle two. (However we conventionally define the median to be half-way between these.)
It is possible to give a unique definition of percentiles for all cumulative percentages. However different textbooks and software use different definitions. The precise definition should not be important as long as you are consistent.
This is the same data as described in the first page of the section — annual rainfal in Samaru from 1928 to 1983.