How to calculate the likelihood of future dam storage volumes in Power BI using PERCENTILEX
This video is part of DiscoverEI's DAX for Enviro's series, and walks through an example of how to use Power BI for water resource management. We show how to calculate the likelihood of different dam storage volumes occurring by analysing 120 different modelling scenarios in Power BI using the DAX iterator PERCENTILEX. Watch the video to learn about how to apply these DAX functions and play around with the Power BI report that we created in the video, embedded below.
The Scenario:
Let's imagine that I am a water resources manager of a small town where the primary water supply comes from 3 reservoirs. I have run 120 different scenarios in my water resources model (eWater Source) to provide an indication of what the next 5 year storage volume could look like. I want to analyse the forecast data for an individual reservoir, as well as for the total storage volume. I've imported the data into Power BI - but I'm stuck? What are my options?
DAX Magic:
Introducing DAX Iterators! Iterators in DAX are functions that iterate through all rows of the given table, apply the expression, and then aggregate the result. The first step is to create a simple measure to SUM up the total system storage volume:
Total storage volume = SUM('Water Outlook Forecasts'[Storage Volume (ML)])
And then, we can iterate this calculation across all of our 120 scenarios for the percentile of our choice, using PERCENTILEX.INC:
Forecast Storage Volume (Rare) = PERCENTILEX.INC(Scenarios,[Total storage volume],0.05)
🎦 Check out the video 🎦
Recommended DAX Resources
As mentioned in the recording there are some AMAZING resources out there to help you with your DAX journey. Here is our pick of the bunch:
Power BI Docs: https://docs.microsoft.com/en-us/dax/dax-overview
DAX Guide: https://dax.guide
SQL BI: https://www.sqlbi.com/
RADACAD: https://radacad.com/new-video-course-dax-and-calculations-in-power-bi
Matt Allington: https://exceleratorbi.com.au/blog/
Chris Webb: https://blog.crossjoin.co.uk/
DAX Formatter: https://www.daxformatter.com/
DAX Studio: https://daxstudio.org/
DAX.Do: https://dax.do/
If you have an environmental DAX challenge that you’d like us to tackle in a future video then please write in the comments below or email the team at info@discoverei.com
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