Aggregations are a way of collapsing, summarizing, or grouping data. When you start with raw data from tables or other data sources, the data is often flat, meaning there is lots of detail, but it has not been organized or grouped in any way. This lack of summaries or structure might make it difficult to discover patterns in the data. An important part of data modeling is to define aggregations that simplify, abstract, or summarize patterns in answer to a specific business question. Most common aggregations, such as those using AVERAGE , COUNT , DISTINCTCOUNT , MAX , MIN , or SUM can be created in a measure automatically by using AutoSum. Other types of aggregations, such as AVERAGEX , COUNTX , COUNTROWS , or SUMX return a table, and require a formula created using Data Analysis Expressions (DAX) . Understanding Aggregations in Power Pivot Choosing Groups for Aggregation ...