To make a Box and Whisker Line Graph Follow these steps:
Keep in mind that the key word here is middle. You will be
finding middle by using the median. Then you look at the two halves created by the median and find the medians of the lower half and then the upper half. These sections are called the quartiles.
Use these numbers :
1 2 3 4 5 6 7 8 9
Plot them on a line
1 2 3 4 5 6 7 8 9
Notice 5 would be the middle or
median
Next find the median of 1 2 3 4 and the median of 6 7 8 9
1 and 4 would be eliminated. That leaves 2 AND 3 in the middle. So the median would be 2.5, since we can only have one middle point.
The same thing occurs on the 6789.
6 and 9 would go, leaving the middle or median between 7 and 8. The median on the upper quartile is 7.5
Since 1 2 3 4 are on
one side and 6 7 8 9
are on the other side of 5, you can see that 5 is exactly in the middle. That makes it a median.
Box and Whisker
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The quartiles are similar to a ruler....the median divided it in 2 halves, then each half was in half again.
Q 1 Q 2 Q 3 Q4
1 2 2.5 3 4 5 6 7 7.5 8 9
Quartiles 2 and 3 are your average range.(In the box) Quartile 1 is below average and Quartile 4 is above average. These are the whiskers.
It has been said that the most important numbers can be described as the 5 number summary :
The median, the data points creating the division of quartiles and the two extremes.
