Long description

Diagram showing the quartiles for sample size n = 20. The V-shape has two additional arms, one to the left and one to the right, so the shape now resembles a capital letter M, but with the sides sloping. The numbers represented by x subscript 1, x subscript 2 and so on, ending with x subscript 20 are shown.

The shape starts with x subscript 1, followed, slightly higher and to the right by x subscript 2, Following the same line are x subscript 3, x subscript 4 and x subscript 5. At that point the V formation begins, but there is a gap at the top. The next entry x subscript 6 is level with but to the right of x subscript 5. The same line is followed by x subscript 7, x subscript 8, x subscript 9 and x subscript 10, which is level with x subscript 1. At x subscript 10 there is a gap. The direction changes again and the letters begin to rise. Slightly to the right but level with x subscript 10 is x subscript 11. The letters continue to rise and move to the right until x subscript 15 is reached. This is level with x subscript 6. There is then a gap and the letters move to the right and begin to fall again, starting with x subscript 16 which is level with x subscript 15. They continue down, moving to the right each time, ending with x subscript 20. This is on the same horizontal level as x subscript 11.

There are three clouds, each containing words. Above the diagram the first cloud contains the words ‘Lower quartile’ and has an arrow pointing to the gap between x subscript 5 and x subscript 6 with the arrowhead closer to x subscript 5 than x subscript 6. To the right and at the same level is another cloud, containing the words ‘Upper quartile’, from which an arrow points to the gap between x subscript 15 and x subscript 16 with the arrowhead closer to x subscript 16 than x subscript 15. The third cloud is below the diagram and contains the word ‘Median’. From it an arrow points to the gap between x subscript 10 and x subscript 11, in the middle of the diagram.