This quiz provides a comprehensive assessment of fundamental Power BI concepts, covering core features, essential DAX functions, and key data modeling principles. Designed for those preparing for interviews or seeking to reinforce their foundational Power BI knowledge, these questions focus on easy-level topics relevant to business analytics and data visualization.
Which of the following best describes Power BI?
Explanation: Power BI is primarily a tool used for creating data visualizations and gaining business insights. It is not a programming language, so option B is incorrect. Power BI is not an operating system, eliminating option C, nor is it a web browser as mentioned in option D.
Which component is used for building and authoring Power BI reports on a desktop computer?
Explanation: Power BI Desktop is specifically designed for creating and authoring reports on a local desktop. Power BI Service is used for sharing and collaboration online, not authoring. Power BI Mobile is for viewing reports on mobile devices, and Power Query Add-in is a feature used primarily in Excel.
What is the primary purpose of DAX (Data Analysis Expressions) in Power BI?
Explanation: DAX is a formula language that allows users to perform calculations and create custom logic. It is not used for designing interfaces or dashboards (option B), managing user permissions (option C), or setting up automated emails (option D).
In Power BI, what is the main difference between a calculated column and a measure?
Explanation: Calculated columns operate at the row level and are stored in the model, while measures are evaluated each time a visual needs them. Option B is wrong, as both can be used in visuals. Option C incorrectly associates storage modes, and option D misrepresents their functions.
What is the main role of Power Query in Power BI?
Explanation: Power Query is used for ETL tasks—Extract, Transform, and Load. It does not focus on dashboard design (option B), security (option C), or automating subscriptions (option D). Its primary role is to manage and prepare data before analysis.
How is Row-Level Security (RLS) implemented in Power BI?
Explanation: RLS involves creating security roles with filters within the report, then assigning users to those roles. Encrypting data (option B) is not specific to RLS, disabling DirectQuery (option C) doesn't enforce row-level access, and calculated tables (option D) are for data modeling.
When should you consider using DirectQuery in a Power BI project?
Explanation: DirectQuery is ideal for very large datasets, as it allows queries to be executed directly against the data source and keeps information up-to-date. Option B is the opposite, as DirectQuery avoids storing data locally. Options C and D do not relate to DirectQuery's real purpose.
In a star schema data model, what surrounds the central fact table?
Explanation: A star schema has a central fact table and is surrounded by dimension tables, which provide context for the facts. Calculated measures (option B) and DAX functions (option D) are not physical entities. Security roles (option C) pertain to access control, not data modeling.
What is the main function of a Power BI Gateway?
Explanation: A gateway acts as a bridge, allowing Power BI services to refresh data from on-premises sources. It does not create mobile reports (option B), monitor activity (option C), or optimize DAX (option D). Its main use is enabling secure data connectivity.
In Power BI, what are dataflows mainly used for?
Explanation: Dataflows help transform and store processed data independently in the cloud, making it reusable. They are not for creating visuals (option B), managing permissions (option C), or defining table relationships (option D). Their real value is in ETL operations in the Power BI ecosystem.
What is the primary difference between Power BI Desktop and Power BI Service?
Explanation: Power BI Desktop is meant for report development, while the Service is mainly for hosting, collaboration, and sharing. Desktop can work offline, so option B is not true. Option C is wrong; Service works on web and desktop. Option D incorrectly claims that Service stores data locally.
What does a calculated table in Power BI allow you to do?
Explanation: Calculated tables are generated using DAX expressions and can be used for advanced modeling or custom groupings. They do not involve drawing on reports (option B), changing colors (option C), or automation of emails (option D). Their purpose is enhancing data models.
What defines a relationship between two tables in Power BI?
Explanation: Relationships connect tables through matching fields, enabling data to link across tables. Merely sharing a workspace (option B), having the same names (option C), or simultaneous publishing (option D) do not establish relationships in the data model.
What does the FILTER function in DAX return?
Explanation: The FILTER function returns only those rows matching the filter condition. Option B refers to the FIRST function, option C describes VALUES or DISTINCT, and option D does not describe FILTER's behavior.
What is a key benefit of using incremental refresh in Power BI?
Explanation: Incremental refresh updates only the data that has changed, making refreshes faster and more efficient. Sorting rows (option B), hiding columns (option C), and changing fonts (option D) are unrelated to incremental refresh's function.