A box plot shows the minimum, lower quartile, median, upper quartile and maximum. A quarter of the data lies in each section, so 75% of the values are above the lower quartile.
To compare two box plots, compare the medians (which group is higher on average) and the interquartile ranges (which group is more consistent). Write your comparison in context, for example: the boys' times were higher on average, but the girls' times were more spread out.
Worked example
A box plot of 20 values has lower quartile 30. About how many values are above 30?
- 75% of the data is above the lower quartile.
- 75% of 20 = 15.
Answer:about 15 values
Key words
- distribution
- how data is spread out
- interquartile range
- the width of the box
- in context
- using the words of the question
Practise this
New questions every time.
Common Core-referenced: HSS-ID.A.1, HSS-ID.A.3