Qlik Fractile Function calculation logic

[yaoyuzhang]

Hi, 

I am a newbie in Qlik.

I am trying to calculate the 20th and 80th percentile, but I don't quite understand the calculation logic of Qlik for my data set.

ID        Values

1          84,17564052

2  

3  

4  

5  

6  

7  

8           28,83317613

Because there are null values in my data, When I created the calculation, the following value was returned :

Fractile(Values, 0.2) = 39,901669008

Fractile(Values, 0.8) = 73,107147642

Fractile(Values, 0.5) = 56.504408325 = Median  ( test with Median , it's  correct ) 

I am confused about the other two calculation results. Is it my fault or is this function wrong?

Can you help me understand? 

Thank you.

[igoralcantara]

This is new to me, I have been using this function, and it works fine. Would you mind sharing the data or a sample? I would love to perform a couple tests on my end.

[igoralcantara]

In the mean time, here is the official documentation:

Fractile - chart function | Qlik Cloud Help

[marcus_sommer · Accepted solution]

The calculation is (a bit manually done) for 0.2:

28,83317613 + ((84,17564052 - 28,83317613) * 0.2)

If it's not what you want you may replace the NULL with ZERO in the data-set (per mapping and/or NULL variables and/or if-queries ...). Helpful may also to play a bit with the numbers and the logic in Excel because the quantil.inkl() worked in the same way.

[yaoyuzhang]

Tnanks a lot,
I understand now, it's the difference in algorithms, thank you