Box/Whisker Plots & Stem-Leaf Plots

A Box Plot, or Box-and-Whisker Plot, is a graphical representation of a dataset that displays the median, quartiles, and extremes of the data. It helps visualize the distribution and identify outliers.

The interquartile range (IQR) is the difference between the first quartile (Q1) and the third quartile (Q3) in a dataset. It measures the spread of the middle 50% of the data.

To find the median, arrange the data in ascending order and locate the middle value. If there is an even number of values, the median is the average of the two middle values.

A Stem-and-Leaf Plot is a method of displaying quantitative data in a graphical format, similar to a histogram, that retains the original data values. Each number is split into a 'stem' (the leading digit(s)) and a 'leaf' (the trailing digit).

A quartile is a type of quantile that divides a dataset into four equal parts. The first quartile (Q1) is the median of the lower half, the second quartile (Q2) is the median of the dataset, and the third quartile (Q3) is the median of the upper half.

To find Q1, arrange the data in ascending order and find the median of the lower half of the dataset.

The purpose of a Box Plot is to provide a visual summary of the central tendency, variability, and distribution of a dataset, making it easier to compare different datasets.

The 'whisker' in a Box Plot extends from the quartiles to the minimum and maximum values of the dataset, excluding outliers.

Outliers in a Box Plot are typically represented as individual points that fall outside the whiskers, which are calculated as 1.5 times the IQR above Q3 and below Q1.

The maximum value is the largest number in a dataset.