Power BI is a collection of software services, apps, and connectors that work together to turn your unrelated sources of data into coherent, visually immersive, and interactive insights. Your data might be an Excel spreadsheet or a collection of cloud-based and on-premises hybrid data warehouses. Power BI is used by data professionals, such as data scientists, data engineers, and business owners, to let you easily connect to your data sources, visualize and discover what’s important, and share that with anyone or everyone you want.
There is a considerable demand for data analysts in the tech industry. Hence, cracking its interview needs a bit of homework. This article contains some of the Power BI interview questions and contains the most probable questions asked during job interviews.
In this article, Femi, a popular data professional from Nigeria, answers some of the most common Power BI Interview Questions asked.
Top 10 Power BI Interview Questions and Answers
1. What do you know about DAX, and have you used it in the past?
“I have extensive experience with DAX. Over the years, I have used aggregate functions like SUM, COUNT, AVG, MAX, and MIN, etc.; filter functions like CALCULATE and FILTER; logical statements like IF and SWITCH; and time intelligence functions like TOTALMTD, TOTALYTD, CALENDAR, PARRALLELPERIOD, DATEADD, and EOMONTH, among others. I can go on if you’d like me to.”
2. The difference between a report and a dashboard
“A report typically presents detailed information, often in a tabular or visual format, providing in-depth insights into specific data sets. Reports are mostly created in Power BI Desktop. On the other hand, a dashboard is a high-level, visual representation that consolidates key metrics and KPIs on a single screen. While a report dives into specific details, a dashboard offers a holistic view, allowing users to quickly grasp overall performance and trends at a glance. Dashboards are usually created in Power BI Service”.
3. What are the building blocks or platforms in Power BI?
The three common building blocks of PowerBI are PowerBI Desktop, PowerBI Service, and PowerBI Mobile. In some circles, the PowerBI Paginated Report is considered to be one of them.”.
4. What are the different data sources you have worked with?
“I have experience with a wide array of data sources in Power BI, ranging from relational databases like SQL Server, Azure SQL DB, Oracle DB, and Redshift. I also have experience with flat files like CSV, text, and Excel sheets as data sources. I have experience with other online sources like SharePoint, APIs, and XML files.”
5. What are the best practices regarding live and import connections?
“Best practices for Power BI connections depend on the scenario. For large datasets or slow data sources, import connections are preferable as they enhance performance. On the other hand, live connections are beneficial when real-time data updates are critical. It’s often recommended to use a combination where you import summary data for performance and connect live for specific details. Careful consideration of data refresh schedules, query folding, and understanding the trade-offs between live and import connections is key to optimizing Power BI performance.”
6. Difference between a calculated column and a measure
In Power BI, a calculated column is like a fixed addition to your dataset, crafted using a formula—it’s there for the long haul. On the flip side, a measure is a dynamic, real-time calculation made with DAX, adapting on the fly based on your report’s context. The calculated column becomes a part of the table, while measures are the agile, responsive players in Power BI, adjusting seamlessly with user interactions and filters depending on the usage.”
7. What kind of licenses are you familiar with in Power BI?
“In terms of Power BI licenses, I’ve worked extensively with Power BI Pro, utilizing its collaboration features and advanced sharing capabilities. I’m also familiar with Power BI Premium, which offers enhanced performance and dedicated cloud resources for more extensive data scenarios.”
8. What is the difference between SUM and SUMX?
“SUM is straightforward; it just adds up numbers in a column. SUMX, on the other hand, is an iterating function. It not only sums things but lets you do calculations or apply conditions while adding up, making it more powerful and flexible.”
9. How do you decide on what visual type to use in PowerBI?
“I believe Power BI visual selection should be use case and message-driven; I decide based on the story I want to tell. Line charts for trends, maps for locations, pie charts showing shares amongst less than 5 variables, etc.—it’s about making the data speak the clearest language.”
10. What are the different views on Power BI?
“In Power BI, you’ve got a Report view where the magic happens, creating cool visuals. Then there’s the Data view, which I believe is now called the Table view, for peeking into your dataset, and the Model view for fine-tuning how tables connect. It’s like a three-step dance to make your data shine.
11. What’s an App in Power BI?
“In Power BI, an App is like a curated bundle of reports, dashboards, and datasets that you can share with others. It’s a neat way to package your insights and make them accessible to a wider audience.”
12. How would you optimize the performance of a Power BI report?
“To optimize Power BI report performance, I’d focus on efficient data modeling, using summarized tables, and avoiding unnecessary visuals. Implementing proper indexing in data sources, reducing visuals on a single page, and optimizing DAX measures for speed would also be part of my strategy.”
13. Are you familiar with Power Query?
“It’s a form of add-on built into many Microsoft tools like Excel, SSAS, and PowerBI, it provides a form of ETL platform, that allows users to extract data from a wide array of sources, transform and manipulate the data, then load the data into the Microsoft tool it is being used.”
14. What is RLS and how would you implement Row Level Security?
“Row-Level Security (RLS) in Power BI is like having a security system for your data. I’d implement it by defining roles and establishing rules that determine what data each role can access. This way, users only see the rows that align with their permissions, ensuring data privacy and integrity.
15. What’s the difference between Filters and Slicers?
“Filters and slices serve similar purposes in power bi but are also different. Filters provide a way to either filter all the report, a particular page, or a particular visual, while slicers are a type of visual that can interact with other visuals to filter within the same page.”
16. What are gateways and what are they used for?
“Gateways in Power BI are the connectors that bridge the gap between cloud and on-premises data sources. They ensure a secure and efficient connection, allowing your Power BI reports to access data stored locally. It’s all about making sure your data can travel seamlessly across different environments.”
17. Do you have any experience with PowerApps and Power Automate?
“I’m well-versed in PowerApps and Power Automate. I’ve utilized PowerApps to create both Canvas and model-driven apps, design intuitive apps, and Power Automate to automate workflows, ensuring smooth data flows and improving overall productivity in various projects.”
18. Can you walk me through your process of creating a dashboard in Power BI?
The typical project follows:
- Collection of business requirements from the stakeholders,
- Decision on the architecture of the project,
- Development of the report based on requirements,
- Testing of the development to ensure it meets requirements,
- productionization of the report,
- Grant access to the different stakeholders.”
This article, “Most Frequently Asked Power BI Interview Questions and Answers,” was written by @Femi_OfMainland and edited by Ndaman Joshua Olayinka
