Data Displays and Analysis
Year 8 statistics focuses on choosing appropriate displays, interpreting data critically, and understanding measures of centre and spread to compare data sets and draw conclusions.
What You Need to Know
Key Concept Diagram
Mean, median, and mode are measures of centre; range and IQR measure spread
Outliers are values far from the rest of the data and can affect the mean significantly
Box plots display the five-number summary: minimum, Q1, median, Q3, maximum
When comparing data sets, comment on both centre and spread
Key Vocabulary
Median
The middle value when data is arranged in order
Interquartile range
The difference between the upper and lower quartiles (Q3 - Q1)
Outlier
A data value that is significantly different from the rest of the data
Box plot
A graph showing the five-number summary using a box and whiskers
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
In the data set {3, 5, 7, 7, 9, 11, 45}, which measure of centre is most affected by the outlier 45?
Question 2
For a box plot with Q1 = 20 and Q3 = 35, what is the interquartile range?
Question 3
Which graph is best for comparing the spread of two data sets?
Key Concepts Summary
- ●Mean, median, and mode are measures of centre; range and IQR measure spread
- ●Outliers are values far from the rest of the data and can affect the mean significantly
- ●Box plots display the five-number summary: minimum, Q1, median, Q3, maximum
- ●When comparing data sets, comment on both centre and spread