What are IQR and the range?

• The three averages (mean,?median?and?mode) measure what is called?central?tendency?– they all give an indication of what is typical about the data, what lies roughly in the middle, etc.
• The?range?and?inter-quartile?range?(IQR) measure how?spread?out the data is.
• These can only be applied to numerical data, and both are easy to work out!

What do I need to know?

1. Range?(Hi-Lo)

• This is the difference between the highest value in the data and the lowest value

• It measures how spread out the data is
• It is simply the?HIGHEST?of all the values?TAKE AWAY?the?LOWEST?of all the values
• For example, find the range of 14, 16, 18, 22

Hi = 22

Lo = 14

Range = 22 – 14 = 8

Hi = 22

Lo = 14

Range = 22 – 14 = 8

2. Inter-Quartile Range?(IQR)

• This is the difference between the?upper?quartile?and the?lower?quartile
• You know the median splits data into two
• Well as their name suggests, quartiles split the data into four

IQR = UQ - LQ

For example, find the inter-quartile range of the follow data …

20, 23, 32, 35, 37, 38, 43, 45, 47, 49, 52, 56, 58, 58, 59