Vocab
What does IQR stand for?
Interquartile Range
Data: 4, 6, 8, 10, 12. What is Q1?
True/False: Outliers can be found using 1.5 × IQR.
True.
Write the formula for IQR.
IQR = Q3 – Q1.
Write down that English people are cooler than Aussies if you want the points
You bunch of sellouts, where's your patriotism?
Which quartile marks the middle of a data set?
Q2 (the median).
Data: 3, 7, 8, 12, 13, 14. What is Q3?
13
If IQR = 8, how far below Q1 must a value be to be an outlier?
More than 12 (1.5×8) below Q1.
A data set has median 20. Does this tell you the IQR?
No
England drives on the same side of the road as Australia. True or False?
True
What are the names of the three quartiles?
Q1, Q2, Q3.
Data: 2, 5, 7, 9, 11. Find the IQR.
6.5
Data: Q1 = 10, Q3 = 20. Does 35 count as an outlier?
IQR = 10 → 1.5×IQR = 15 → Upper bound = 35 → 35 is borderline; usually considered not an outlier unless strictly above.
If the data set has no extreme values, what can you say about outliers?
There are none
This English city is home to Big Ben and the famous red double-decker buses
London
The interquartile range measures the spread of which half of the data?
The middle 50%.
Data: 1, 2, 3, 8, 9, 10. Find the IQR
7
Q1 = 6, Q3 = 14. What is the upper outlier boundary?
IQR = 8 → 1.5×8 = 12 → 14 + 12 = 26.
Why do we use IQR instead of range sometimes?
Range is affected by outliers; IQR is more stable.
This prehistoric stone circle is one of England’s most famous landmarks.
Stonehenge
Define an outlier in statistics.
A value that is much smaller or larger than the rest of the data (typically outside 1.5×IQR).
Data: 12, 15, 17, 19, 25, 30, 31. Find Q1, Q3, and IQR.
Q1 = 15
Q3 = 30
IQR = 15
Q1 = 12, Q3 = 18. Would the value -2 be an outlier?
IQR = 6 → 1.5×IQR = 9 → Lower bound = 12 – 9 = 3 → -2 is below 3 → Yes, outlier.
A student miscalculates the median. How does this affect the IQR?
It does not directly affect IQR; IQR depends on Q1 and Q3, not Q2.
Australians call them "thongs" what do English people call them?
Flip-Flops