Alternative to CONFIDENCE.NORM function (function is missing in Excel 2016)

[JollyRoger01]

I have some DAX calculated columns in which I want to use CONFIDENCE.NORM to return the upper and lower bounds of a forecast based on a 95% confidence interval, however it seems that Excel 2016 does not have this function. I am wondering if anyone knows an alternative to this that I can use in Excel 2016. I have attached the workbook below - the problem calculation is in the Facts_Calc table of the Data Model.

Forecast Problem 

[Anonymous]

Well, the easiest way is to take a look at how the formula for the bounds is written and then calculate it in your model from scratch.

[JollyRoger01]

Is there a process to look at the inner working of Excel formulas?

[Anonymous]

You can either go to the online documentation of the Excel functions or find the definition of the functions in places like Wikipedia, Wolfram Alpha or any good source of mathematical knowledge.