Long description

Diagram showing the quartiles for sample size n = 18. 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 18 are shown.

The shape starts on the left with x subscript 1, followed, slightly higher and to the right by x subscript 2, Following the same line are x subscript 3 and x subscript 4. At that point the V formation begins, but there is a gap at the top. The next entry x subscript 5 is level with but to the right of x subscript 4. The same line is followed by x subscript 6, x subscript 7 and x subscript 8, which is level with x subscript 1. Continuing in the same direction leads to x subscript 9, which is at a lower level than x subscript 1. At x subscript 9 there is a gap. The direction changes again and the letters begin to rise. Slightly to the right but level with x subscript 9 is x subscript 10. They continue to rise and move to the right until x subscript 14 is reached. This is level with x subscript 5. There is then a gap and the letters then begin to fall again, starting with x subscript 15 which is level with x subscript 14. They continue down, moving to the right each time, ending with x subscript 18. This is on the same horizontal level as x subscript 1.

There are three clouds, each containing words. The first contains the words ‘Lower quartile’ and has an arrow pointing to the gap between x subscript 4 and x subscript 5 with the arrowhead closer to x subscript 5 than x subscript 4. 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 14 and x subscript 15 with the arrowhead closer to x subscript 14 than x subscript 15. Below the diagram a third cloud contains the word ‘Median’. From it an arrow points to the gap between x subscript 9 and x subscript 10, in the middle of the diagram.