Countdown to Exams - Day 22 - Quartiles and box plots
For day 22 we extend beyond plotting cumulative frequency graphs and look at Quartiles and box plots. Once the graph has been created, we tend to examine it in more detail by looking at the quartiles which are situated at 25%, 50% (the Median) and 75%. An important area we analyse is the Inter Quartile Range (IQR), this tells about the spread of data of the middle 50% of the data.
A box plot is extracted from a cumulative frequency diagram and is made up of five key elements; Highest and lowest value, Upper and lower quartile (75% and 25%) and the median. These become useful when we want to compare tow or more sets of data.
Matt will go through quartiles and IQR and what they mean and then lead into how Box plots are created and how to analyse the data within them.
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