# Thread: Explanation of QUARTILE calculation (XP)

1. ## Explanation of QUARTILE calculation (XP)

Can someone please direct me to a concise (and understandable explanation) of how the QUARTILE function calculates the 1st and 3rd quartiles when there are very few data points (eg 8 or so)? It's pretty straightforward when there is lots of data, but when there are few data points, it's not as clear.

Thanks!

Larry

2. ## Re: Explanation of QUARTILE calculation (XP)

If you have 8 data points, Quartile 1 lies between point 2 and 3, at a distance of 3/4 of point 2 relative to point 3. So the function takes the second value and adds 0.75 times the difference with the third value. Same for the second: the median. Since there is no center value, it takes the fourth value and adds half of the difference with the fifth. Same goes for the 3rd quartile: it takes the 6th value and adds 0.25 times the difference with the seventh value.

So the numbers 1,2,3,4,5,6,7,8 yield 2.75, 4.5 and 6.25 respectively

whereas

2,4,6,8,10 yield 5.5, 9 and 12.5

3. ## Re: Explanation of QUARTILE calculation (XP)

Jan Karol,

Wonderful explanation - thanks!!!!!!!!!!!!!!!!!!!!!!!

Larry

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•