Kaplan Meier Survival Curves

[Greg_Deckler]

@Buzzshot43 posted a question on KM Survival Curves here:

https://community.powerbi.com/t5/Desktop/KM-Survival-Curve-in-Power-BI/m-p/326809#M145836

The post refers to the following Tableau article:

https://www.linkedin.com/pulse/survival-curves-tableau-hr-data-chris-short/

So, figured I'd give it a shot and have gotten part of the way there but was hoping the community could help me finish this off.

I am using the dataset from the Tableau article referenced above and am trying to recreate this using pure Power BI (no R). I imported the data as HRData. The data looks like:

ID,Name,Hire Date,Termination Date,Status,Department

1,Inez Laurie,4/23/2010,9/2/2015,Inactive,HR

2,Yasuko Scruton,1/20/2010,,Active,Sales

...

So, in the dataset, I created the following custom columns:

Years = IF([Status]="Active",DATEDIFF(HRData[Hire Date],TODAY(),YEAR),DATEDIFF(HRData[Hire Date],HRData[Termination Date],YEAR))

Event = IF(HRData[Status] = "Inactive",1,0)

Count = 1

I created a Calendar table using 

Calendar = CALENDARAUTO(12)

Which I tied to Termination Date (relationship)

I created a measure to give me a running total for Count:

Count running total in Date = 
CALCULATE(
	SUM('HRData'[Count]),
	FILTER(
		ALLSELECTED('Calendar'[Date]),
		ISONORAFTER('Calendar'[Date], MAX('Calendar'[Date]), DESC)
	)
)

I created a measure for d_i:

d_i = SUM(HRData[Event])

I created a measure for n_i

n_i = COUNTROWS(HRData) + CALCULATE(COUNTROWS(HRData),ALL(HRData)) - [Count running total in Date]

This is where things get a little messy. The formula for KM goes something like:

(Previous Value of KM) * (1-d_i/n_i)

So, what I did was create three measures like this:

KM1 = 1-[d_i]/[n_i]

KM-1 = CALCULATE([KM1],DATEADD('Calendar'[Date],-1,DAY))

KM = [KM-1]*[KM1]

The thought here was that I could have a continuous line chart by [Date] in Calendar and calculate KM1 for that date, KM1 for the previous date (KM-1) and then use those to calculate KM.

But, I'm not really getting what I expected and was wondering if someone could take a look and see if they can get this to work or have a better way.