what is a five number summary
The five-number summary is a descriptive statistic that provides information about a set of observations.It consists of the five most important sample percentiles 1  : the sample minimum (smallest observation). 2  the lower quartile or first quartile.he median of the first group is the lower or first quartile, and is equal to (0 + 1)/2 = 0.5. The median of the second group is the upper or third quartile, and is equal to (27 + 61)/2 = 44. The smallest and largest observations are 0 and 63. So the five-number summary would be 0, 0.5, 7.5, 44, 63.