Whitepapers allow you to explore Power BI topics at a deeper level. Here you can find a list of available whitepapers for Power BI.

Whitepaper Description
Microsoft Power BI Premium Describes Power BI Premium, both as it exists when launched and also how it will evolve.
Best design practices for reports and visuals Provides best practices for designing reports in Power BI.
Advanced Analytics with Power BI Describes the advanced analytic capabilities of Power BI, including predictive analytics, custom visualizations, R integration, and data analysis expressions.
Bidirectional filtering Explains bidirectional cross-filtering in Power BI Desktop (the whitepaper also covers SQL Server Analysis Services 2016, both have the same behavior).
DirectQuery in SQL Server 2016 Analysis Services For SQL Server 2016, DirectQuery was redesigned for dramatically improved speed and performance, however, it is also now more complex to understand and implement.
Governance Provides a framework for increasing the return on investment related to Power BI
Security Provides a detailed explanation of security within Power BI.
Securing the Tabular BI Semantic Model This paper introduces the security model for tabular BI semantic and Power BI. You will learn how to create roles, implement dynamic security, configure impersonation settings, manage roles, and choose a method for connecting to models that works in your network security context.

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