Module 2: 2-2: Displaying and Summarizing Data pt. 2

interquartile range

range of the middle half of data; based on 4 quartiles

p^th percentile

value where p% falls below p^th percentile and (100-p)% fall above it

• median is 50th percentile

lower quartile(Q1)

25th percentile:

• separates bottom 25% measurements from the top 75%

• median of measurements that fall below overall median

upper quartile(Q3)

75th percentile:

• separates top of 25% from the bottom 75%

• median of measurements that fall above overall median

IQR Formula

• is not affected by the outlier

• small: clustered around center

• large: scattered from center

five number summary

set of measurements:

• minimum

• Q1

• median(M)

• Q3

• maximum

Boxplot

shows the center, spread, and symmetry/skewness at the same time; useful for comparing groups

boxplot properties

• symmetric distribution: median line in center of box and whiskers of equal length

• skewed right: median line left of center and long right whisker

• skewed left: median line right of center and long left whisker

time plot

plots each observation against the time at which it was measured