Top 20 Power BI Interview Questions and Answers

Top 20 Power BI Interview Questions and Answers:

Microsoft introduced Power BI to deliver analytical capabilities, and upgrade it in order to deliver interactive reports. Power BI is one of the most effective business intelligence tools used by most IT firms and is an essential tool for business analytics. Power BI is used in excel spreadsheets, cloud-based applications and on-premises data sources. It is part of the Microsoft Platform Presentation. As an integral part of data analytics, Power BI is in demand, and here are the top 20 Power BI interview questions and answers, which grasp the essential fundamentals of Power BI concepts.

1. What is Power BI?

Power BI is a business analytics service owned by Microsoft, allowing the servers to connect, transform and visualise their data, and enabling them to create interactive reports and dashboards and share them with others so that they have access from multiple devices. Power BI is used in excel spreadsheets, cloud-based applications and on-premises data sources. It is part of the Microsoft Platform Presentation.

2. Difference between Power BI and Tableau.

Power BI and Tableau are both business analytics tools, used for purposes of data visualisation, data analysis and curating report. Key differences between Power BI and Tableau are:

3. Why use Power BI?

Power BI is a user-friendly interface, also for non-technical people, and supports data visualisations and analysis by allowing the creation interactive and appealing charts, graphs and other visualisations. The data modelling capabilities allow users to do data transformation, and data cleaning. Users can transform the raw data into visually appealing, smart and valuable data that facilitates the better representation of data. The dashboards can be accessed from a variety of devices, which enables them to stay updated. Reports can be shared as well on these dashboards, increasing collaboration and data-driven decision-making by the team.

4. What is Power Query?

A data connection and transformation tool built into Microsoft Excel and other Microsoft applications, which allows writing queries once and then running with a simple refresh. It connects a wide variety of data sources such as files, databases and web services that transforms data, by using applications like custom calculations and conditional logic, according to the needs of the users.

5. What are filters in Power BI?

They enable to filter of essential information from rows and columns. They are mathematical and logical conditions applied to data to extract information. They limit the data displayed in reports or visualisation on different criteria. Different types of filters are available in Power BI.

• Manual filters
• Include/Exclude filters
• Drillthrough filters
• URL filters
• Pass-through filters
• Auto filters
• Cross-Drill filters

6. What are custom visuals in Power BI?

They are data visualisation tools, added to business intelligence tools, presenting data in a customisable manner, and these visuals can be built by users including charts, graphs, maps and other interactive displays in presentations and facilitating informed decisions. Languages like JQuery and JavaScript are used to create custom visuals in Power BI.

7. What is GetData in Power BI?

Get Data allows users to import data from data sources such as excel spreadsheets, and SQL databases into Power BI for further processing and analysis, and the connectors feature organises the data into a structured framework, and once data is imported, users can manipulate data into data visualisations which would enable data-driven decisions.

8. What are the limitations of using Power BI?

While Power BI is a powerful business intelligence tool, there are some limitations that users should be aware of:

1. Data size limitations: Power BI has some restrictions on the amount of data that can be loaded into the tool. The amount of data that can be loaded depends on the license type and the available resources, and larger data sets may require additional configuration and optimization.
2. Real-time data limitations: While Power BI supports real-time data streaming, it may not be the best tool for real-time reporting or data processing. It may require additional configuration or the use of external tools to handle real-time data.
3. Steep learning curve: Power BI is a complex tool with a variety of features and functions, which may take some time to learn and master. Users with limited technical or data analysis skills may find it challenging to use the tool effectively.
4. Licensing costs: While Power BI offers a free version, users may need to purchase a license to access advanced features, such as live connections to data sources, collaboration features, or advanced security and governance options.
5. Dependence on external tools: While Power BI offers many features, it may not have all the required capabilities for specific business needs. Users may need to rely on external tools or custom development to fill any gaps or limitations.

9. Name the different connectivity modes available in Power BI.

There are several main connectivity modes offered by Power BI to several other data sources.

• Import: importing data from data source to Power BI for data visualisation and analysis. Stored in a compressed im-memory cache, changes to the data source will require a refresh.
• Direct Query allows users to query large and complex data sets in real-time and connect with the data source.
• Live connections help to connect with on-premises data sources without storing the data in the Power BI service. A query using a live connection will directly query the existing analysis services model.
• Power BI datasets: they create and manage datasets in Power BI that can be used for reporting and analysis. This mode is useful for creating custom data models, combining data from multiple sources, and providing a single source of truth for the organization.
• Power BI Dataflows: This allows users to extract, transform, and load data from a variety of sources into the Power BI service. Dataflows can be used to transform and combine data, create reusable data models, and maintain a consistent data source for reporting and analysis.

10. What are the different types of refresh options provided in Power BI?

In order to ensure that data in reports and dashboards are updated, the different refresh options available in Power BI are

• Users can refresh a single visual or the entire report by the ‘refresh button’ on the Power BI interface.
• Scheduled reports and dashboards can be refreshed at specific intervals of time, depending on the Power BI license.
• Live connection updates reports and dashboards automatically as the data changes.
• Direct Query allows users to query large and complex data sets in real-time and connect with the data source. Any changes made to the data source are reflected in the report immediately.
• Incremental refresh helps to refresh large datasets that take time to refresh. Only the data changes since the last refresh are updated which reduces the time to refresh the data source.
• Hybrid Refresh: This refresh mode is used for reports that contain data from both cloud and on-premises data sources. The on-premises data is refreshed using a Power BI Gateway, while the cloud data is refreshed using the cloud-based refresh mechanisms.

11. What is a dashboard in Power BI?

A single-layer presentation sheet of multiple visualisation reports, a dashboard is a collection of data visualisations that presents a story, drilling through the page, bookmarks and selection pane to create tiles and integrate URLs.

12. Explain how relationships are defined in the Power BI desktop.

Relationships are defined in two manners:

• Relationships are manually defined using primary and foreign keys.
• Automatic feature of Power BI automatically detects the relationship between tables and creates them.

13. What is DAX in Power BI?

Data Analysis Expressions (DAX) is a programming language to create columns, measures and customise tables. It has a collection of operators and functions to use in a formula, to calculate and return values.

14. What is row-level security?

Relying on filters, row-level security limits the data accessible to users for viewing, and enables users to control the data at the row level. Users can define the filters to control the data that each role can access. The filters are applied according to the views of the user, allowing them to have access to relevant data.

15. Why should you apply general formatting to Power BI data?

Users apply general formatting to Power BI to categorise data and identify data making it easier to work and apply.

16. What do you mean by the content pack?

A pre-built collection of dashboards and reports shared and installed in Power BI, content packs provide a set of pre-configured data visualisations and data connections, to have easier access to data analysis and reporting. Content packs are created by data providers, such as Microsoft, Salesforce, and Google Analytics, who package the data and visualizations into a single file that can be easily installed and customized by Power BI users. These content packs may include pre-built reports, dashboards, and data models, as well as connections to specific data sources. Users can install a content pack by selecting it from the Power BI service or by downloading it from the Power BI marketplace. Content packs are a useful way to accelerate the process of building reports and dashboards, by providing a starting point for analysis and data visualization. They can also help to ensure that reports and dashboards are consistent across an organization, by providing a standard set of visualizations and data connections.

17. What is bi-directional cross-filtering?

Bi-directional cross-filtering filters data modellers helping them to establish how to let flow for data and relationships between tables. Data is selected from one visual to another visual in the dashboard. Users can dynamically filter data from multiple views to have a comprehensive understanding of the data set. For example, in a dashboard showing sales by region and by product, bi-directional cross-filtering would allow a user to select a specific region, and see the corresponding sales figures for each product in that region, as well as select a specific product and see the corresponding sales figures for each region.

18. What is grouping?

You can group the data in your visuals into chunks. Custom groups of data are created using specific criteria. You can create a group in Power BI:

• Select the column that you want to group by in the Fields pane.
• Right-click on the column and select "New Group".
• In the Group dialog box, provide a name for the new group.
• Define the criteria for the group by using the "Add Grouping" button.
• Once you have defined the group, click "OK" to create the new group.
• You can also use the "Advanced" option in the Group dialog box to specify more complex grouping criteria

19. Explain responsive slicers in Power BI.

A developer can resize responsive slicers in Power BI to different sizes and shapes, from horizontal tile to square to vertical, and the collected data in the container is reorganised to find a match. They are an excellent choice to display commonly used filters on the report access for visualisation that makes information to be easily accessible.

20. Which in-memory analytics engine does Power Pivot use?

Power Pivot uses the xVelocity in-memory analytics engine, also known as the VertiPaq engine, to store and process large amounts of data within Excel. This engine is designed to perform high-speed, in-memory data analysis on large datasets, and is optimized for handling complex calculations and queries. It uses a column-based storage model, which allows for fast compression and decompression of data, making it possible to work with large datasets in a desktop environment. The xVelocity engine is also used in other Microsoft products, such as SQL Server Analysis Services and Power BI.