Show quartile based on rank.

[Mera9]

I am trying to create a measure that shows a quartile based on the rank of the vendor. 

Currently, there are around 680 Vendors and it will be dynamic.
There should be 4 quartiles - Top 25%, Top 50%, Bottom 50%, Bottom 25%.
Here is the formula that I have now but it doesn't work correctly and I don't know how to improve it:

Vendor Quartile =
VAR TotalVendors = COUNTROWS(vDIM_Vendor_Daily)
VAR QuartileSize = ROUNDUP(TotalVendors / 4, 0)
RETURN
SWITCH(
TRUE(),
[OTIF Rank] <= QuartileSize, "Top 25%",
[OTIF Rank] <= 2 * QuartileSize, "Top 50%",
[OTIF Rank] <= 3 * QuartileSize, "Bottom 50%",
"Bottom 25%"
)

Please help!

[adudani · Accepted solution]

hi @Mera9 ,

maybe try using this, if it fits your use case: Calculate Percentile in Power BI (youtube.com)

else another dax function that may come in handy: PERCENTILE.INC function (DAX) - DAX | Microsoft Learn
usage shown here : PERCENTILE.EXC, PERCENTILE.INC, PERCENTILEX.EXC, PERCENTILEX.INC - DAX Guide (youtube.com)

if this doesn't resolve the issue, kindly provide sample input and output data masking sensitive information and in a usable format ( table, excel etc.)