Describing data

When a data set is listed in a stem‑and‑leaf plot or a frequency table, the *mode* is simply the value that appears most often. In a stem‑and‑leaf plot you count how many leaves each stem has; the stem with the greatest leaf count (or the leaf that repeats most within that stem) gives the modal value. The *median* is the middle value when all observations are arranged in order. If the total number of observations, $n$, is odd, the median is the $(n+1)/2$‑th term; if $n$ is even, it is the average of the $n/2$‑th and $(n/2)+1$‑th terms. For grouped data you may need to expand the frequencies into a list, then locate the middle position(s).