Hristo Hristov writes some DAX:
At times when using Power BI, you want to combine your data to produce an aggregated value. The aggregation is performed over some criteria – frequently this may be time (year, month, date) or a categorical value. Some popular aggregation functions to apply can be Sum, Average, Maximum, Minimum, or Count. Typically, Power BI applies certain aggregations by default when adding data fields to visualizations. What if you wanted to create your own data aggregations? To achieve better understanding of the underlying data, how can you attain fine-grained control over the aggregations?
Read on for several DAX measures, including totals, running totals, moving averages, and day over day changes.