Percentile Function

[Merle_Hanson]

I am trying to get a 90th percentile number out of a list of numbers.
Example... Number List = 1,2,3,4,5,6,7,8,9,10,11 and the 90th percent number
would be 10 Number List = 2,3,4,5,6,7,8,9,10,11,12 and the 90th percent number
would be 11 Number List = 4,5,5,6,6 and the 90th percent number would be 6 But
not sure how to do this... Excel has a function -> Percentile({1,2,3,4},0.3) =
1.9 <- this is 30th percent though... I can't seem to figure out how to get CF
to spit it out... Do I build a number list, and array or what... I am pulling
my hair out - any help is appreciated... Merle

[jdeline]

I'm assuming that the definition of the 90th percentile is that number in a
list that is greater than 90% of all numbers and less than 10% of all numbers.
If this is correct, then sort your list , count the number of elements in the
list, multiply the count by 0.9 and use the result in a ListGetAt statement.
See code below.



<CFSET stuff = "1,3,7,5,4,8,2,4,3,6,5,1,8,4">
<CFSET stuff = ListSort(stuff, "Numeric", "Asc")>
<CFSET count = ListLen(stuff)>
<CFSET i = Round(count * 0.9)>
<CFSET ninty = ListGetAt(stuff, i)>

[Merle_Hanson]

Close I think thanx... I'm trying different number lists... For example -
12.2,14,33.4,3.7,8,6.5,4.75 is a list of 7 numbers... And your code gets me the
number 14 as 90th %... When I do same code in excel - I get 21.76 as number...
So not sure how to get that 21.76 number...

[jdeline]

There appear to be more than one definition of percentile. Mine is one of them; you can get more information about this wierdness at [url]http://cnx.rice.edu/content/m10805/latest/[/url].

[Merle_Hanson]

yes - that is where i started...
I'm at a loss though... Part of me say ur solution is correct - but doing same numbers in Excel - relates there is a different number...