Top Power BI Interview Questions In 2021

Microsoft Power BI is popular for a reason. This self-service business intelligence cloud service not only is highly rated—it’s free. PCMag reviewer Pam Baker says Power BI “does a fantastic job of combining power analytics with a user-friendly user interface (UI) and remarkable data visualization capabilities,” and adds, “It’s one of the best BI tools on the market and is one of our three Editors’ Choice recipients.”

Industries, where Power BI training comes in handy, include retail, manufacturing, telecommunications, and professional services. The service is a game-changer because it allows non-technical people to easily create graphical reports of data, filter data, share it with others, and much more—no IT department required, meaning even small companies can use it successfully.

Whether you’ve already begun a career in business intelligence, data analysis, ETL (extract, transform, load) and data warehousing or another data-driven area, or you just want to add to your job skills and marketability in the business world, getting a Power BI certification is a smart move. And when you’re preparing for a job interview, make sure you consider these answers to Top Power BI interview questions. While this isn’t a full Power BI tutorial, it will help you get started understanding the basics.

Power BI Interview Questions

1. What is Power BI?

Power BI is a business analytics tool developed by Microsoft that helps you turn multiple unrelated sources of data into valuable and interactive insights. These data may be in the form of an Excel spreadsheet or cloud-based/on-premises hybrid data warehouses. You can easily connect to all your data sources and share the insights with anyone.

2. List out some benefits of using Power BI.

Here are some benefits of using Power BI:

• It helps build interactable data visualization in data centres
• It allows users to transform data into visuals and share them with anyone
• It establishes a connection for Excel queries and dashboards for fast analysis
• It provides quick and accurate solutions
• It enables users to perform queries on reports using simple English words 

3. List out some drawbacks/limitations of using Power BI.

Here are some limitations of using Power BI:

• It does not accept file sizes larger than 1 GB and also doesn’t mix imported data, which is accessed from real-time connections
• There are very few data sources that allow real-time connections to Power BI reports and dashboard
• Dashboards and reports are only shared with users logged in with the same email address
• Dashboard doesn’t accept or pass user, account, or other entity parameters

4. What are some of the differences in data modeling between Power BI Desktop and Power Pivot for Excel? 

Power Pivot for Excel supports only single directional relationships (one to many), calculated columns, and one import mode. Power BI Desktop supports bi-directional cross filtering relationships, security, calculated tables, and multiple import options. 

5. Name the different connectivity modes available in Power BI? 

There are three main connectivity modes used in Power BI are.

SQL Server Import

An SQL Server Import is the default and most common connectivity type used in Power BI. It allows you to use the full capabilities of the Power BI Desktop. 

Direct Query

The Direct Query connection type is only available when you connect to certain data sources. In this connectivity type, Power BI will only store the metadata of the underlying data and not the actual data.

Live Connection

In this connectivity type, data is not stored in the Power BI model. All interaction with a report using a Live Connection will directly query the existing Analysis Services model. There are only 3 data sources that support the live connection method -  SQL Server Analysis Services (Tabular models and Multidimensional Cubes), Azure Analysis Services (Tabular Models), and Power BI Datasets hosted in the Power BI Service

6. What are the different types of refresh options available in Power BI? 

There are four main types of refresh options available in Power BI -

• Package refresh - This synchronizes your Power BI Desktop or Excel, file between the Power BI service and OneDrive, or SharePoint Online.
• Model or data refresh - This refreshes the dataset within the Power BI service with data from the original data source.
• Tile refresh - This updates the cache for tile visuals every 15 minutes on the dashboard once data changes.
• Visual container refresh - This refreshes the visual container and updates the cached report visuals within a report once the data changes.

7. Name the data sources can Power BI connect to? 

There are a number of data sources that can be connected to Power BI, which are grouped into three main types:

Files

Data can be imported from Excel (.xlsx, .xlxm), Power BI Desktop files (.pbix) and Comma Separated Values (.csv). 

Content Packs

These are a collection of related documents or files stored as a group. There are two types of content packs in Power BI:

• Content packs from services providers like Google Analytics, Marketo or Salesforce and
• Content packs created and shared by other users in your organization. 

Connectors

Connectors help you connect your databases and datasets with apps, services, and data in the cloud.

8. What is a dashboard in Power BI? 

A dashboard is a single layer presentation sheet of multiple visualizations reports. The main features of the Power BI dashboard are:

• It allows you to drill through the page, bookmarks, and selection pane and also lets you create various tiles and integrate URLs
• A dashboard can also help you set report layout to mobile view

9. Explain how relationships are defined in Power BI Desktop? 

Relationships between tables are defined in two ways: 

• Manually - Relationships between tables are manually defined using primary and foreign keys
• Automatic - When enabled, this automated feature of Power BI detects relationships between tables and creates them automatically

10. Can you have more than one active relationship between two tables in a Power Pivot data model?

No. There can be multiple inactive relationships, but only one active relationship between two tables in a Power Pivot data model. Dotted lines represent inactive relationships and continuous lines represent active relationships.

11. Can you have a table in the model which does not have any relationship with other tables? 

Yes. There are two main reasons why you can have disconnected tables:

• The table is used to present the user with parameter values to be exposed and selected in slicers 
• The table is used as a placeholder for metrics in the user interface

12. What is the CALCULATE function in DAX?

The CALCULATE function evaluates the sum of the Sales table Sales Amount column in a modified filter context. It is also the only function that allows users to modify filter context of measures or tables.

13. Where is data stored in Power BI? 

Data is stored in fact and dimension tables. 

• Fact tables: It is the central table in a star schema of a data warehouse. It stores quantitative information for analysis.
• Dimension tables: It is just another table in the star schema of a data warehouse. It stores attributes and dimensions that describe objects stored in a fact table.

14. What are the different views available in Power BI Desktop? 

There are three different views in Power BI, each of which serves a different purpose: 

• Report View - In this view, users can add visualizations and additional report pages and publish the same on the portal.
• Data View - In this view, data shaping can be performed using Query Editor tools
• Relationship View - In this view, users can manage relationships between datasets

15. What is the format available in Power BI?

• Power BI Desktop—for desktop computers
• Power BI service—an online SaaS (software as a service)
• Mobile Power BI apps—for iOS and Android devices

All of these can be used in conjunction. For example, you might create a report on your desktop, and then publish and share it online so that colleagues on mobile devices can read it. 

16. Describe the building blocks of Power BI.

• Visualizations

  Visualization is a chart, graph, or similar visual representation of data.

• Datasets

  A dataset is the group of data used to create a visualization, such as a column of sales figures. Datasets can be combined and filtered from different sources using built-in connectors.

• Reports

  A report is a group of visualizations on one or more pages; for example, charts, graphs, and maps can be combined to create a report. 

• Dashboards

  A dashboard lets you share a one-page visualization with others, who can then interact with your dashboard.

• Tiles

  A tile is a visualization on your dashboard or in your report. As the creator, you can move tiles around.

17. What are the main components of the Power BI toolkit, and what do they do?

• Power Query: lets you discover, access, and consolidate info from different sources
• Power Pivot: a modeling tool
• Power View: a presentation tool for creating charts, tables, and more
• Power Map: lets you create geospatial representations of your data
• Power Q&A: lets you use natural language to get answers to questions; for example, “What were the total sales last week?”

18. What is a content pack, and why would you use one?

A content pack is a ready-made, predefined collection of visualizations and reports using your chosen service (for example, Salesforce). You’d use one when you want to get up and running quickly, instead of creating a report from scratch.

19. Describe DAX.

DAX stands for Data Analysis Expressions. It’s a collection of functions, operators, and constants used in formulas to calculate and return values. In other words, it helps you create new info from the data you already have. 

20. What are the three fundamental concepts of DAX?

• Syntax

  This is how the formula is written—that is, the elements that comprise it. The Syntax includes functions such as SUM (used when you want to add figures). If the syntax isn’t correct, you’ll get an error message.

• Functions

  These are formulas that use specific values (also known as arguments) in a certain order to perform a calculation, similar to the functions in Excel. The categories of functions are date/time, time intelligence, information, logical, mathematical, statistical, text, parent/child, and others.

• Context

  There are two types: row context and filter context. Whenever a formula has a function that applies filters to identify a single row in a table, row context comes into play. When one or more filters are applied in a calculation that determines a result or value, the filter context comes into play.

21. Why and how would you use a custom visual file?

You’d use a custom visual file if the prepackaged files don’t fit the needs of your business. Custom visual files are created by developers, and you can import them and use them in the same way as you would the pre-packaged files.

22. What are some of the most common sources for data in the Get Data menu?

Excel, Power BI datasets, web, text, SQL server, and analysis services.

23. What are the categories of data types?

• All
• File
• Database
• Power BI
• Azure
• Online Services
• Other

24. Name some commonly used tasks in the Query Editor.

• Connect to data
• Shape and combine data
• Group rows
• Pivot columns
• Create custom columns
• Query formulas

25. What is grouping, and how would you use it?

Power BI Desktop groups the data in your visuals into chunks. You can, however, define your own groups and bins. For grouping, use Ctrl + click to select multiple elements in the visual. Right-click one of those elements and, from the menu that appears, choose Group. In the Groups window, you can create new groups or modify existing ones.

26. Describe responsive slicers.

On a report page, you can resize a responsive slicer to different sizes and shapes, and the data contained in it will be rearranged to match. If a visual becomes too small to be useful, an icon representing the visual takes its place, saving space on the report page.

27. In Power Query, what is query folding?

This is when steps defined in the Query Editor are translated into SQL and executed by the source database, instead of by your own device. It helps with scalability and efficient processing.

28. Explain the term “M language”.

This is the programming language used in Power Query. It’s a functional, case-sensitive language that’s similar to other programming languages and easy to use.

29. What are the differences between visual-level filters, page-level filters, and report-level filters? 

Visual-level filters filter data within a single visualization. Page-level filters work on an entire page in a report, and different pages can have different filters. Report-level filters filter all the visualizations and pages in the report.

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30. How does the Schedule Refresh feature work?

You can configure an automatic refreshing of data daily or weekly, and at different times. You can schedule only one refresh maximum daily unless you have Power BI Pro. In the Schedule Refresh section, simply use the pulldown menu choices to select a frequency, time zone, and time of day.

31. What information is needed to create a map in Power Map?

Power Map can display visualizations that are geographical in nature. Therefore, some kind of location data is needed—for example, city, state, country or latitude and longitude.

32. Explain Power BI vs. Tableau

Microsoft Power BI and Tableau are both data analytics tools. Power BI has an extensive free version as well as a premium paid version, while Tableau’s free version has limited capabilities. Power BI is considered more intuitive to use than Tableau, as some features in Tableau are hidden behind menus, which makes it harder to learn and use. Power BI has a natural-language query tool, which Tableau doesn’t. Overall, however, Tableau may offer more capabilities for those who are experienced in data analytics. So for the question of Power BI vs. Tableau, Microsoft Power BI is generally considered better for those new to data analytics, especially if they already have experience in Microsoft products such as Excel, Azure, and Office 365.

These are just some of the Microsoft Power BI interview questions you might encounter. To learn more answers and get a career-boosting Power BI certification, sign up for Simplilearn’s Power BI Certification Training today!