16 Power BI Interview Questions With Answers

Power BI is a data analysis and visualisation tool developed by Microsoft.

Currently, it is one of the most sought-after skills for business intelligence analysts in particular and data scientists in general.

This article covers some of the most common Power BI interview questions that you might be asked if you apply for a Power BI related job and the answers to those questions.

The questions get more challenging as you go through the article.

If you are applying for a more advanced data analyst role, you may want to skip ahead to question 9 or 10.

1. What Is Power BI? What Is It Used For?

Power BI is business intelligence software used to make sense of large amounts of data. 

It lets you draw meaningful conclusions, filter results, find trends, segment data and much more. 

This information can be created in a visually appealing report or dashboard that is easy for non-technical users to understand and navigate. 

Since Power BI is cloud-based software, Power BI reports are easy to share with others who can interact with the report, apply filters, and manipulate the data as they require. 

Power BI allows users without deep statistical skills to interrogate very large volumes of raw data. As such, it is self-service business intelligence software that is not confined to use by an IT or data team.

See this article for full details: What Is Power BI?  and The Difference Between Reports And Dashboards In Power BI


2. Briefly Explain Power BI’s Core Building Blocks?

The main building blocks of Power BI are:

  • Datasets: Datasets are the primary source of information for Power BI. Data can be collected from different sources such as Azure, Excel, SQL, Oracle, Text files and more. 
  • Visualisations: Data can be represented in charts, maps, and tables. A key benefit of Power BI is that it makes producing attractive data visualisations very straightforward. 
  • Reports: The information and insights gathered from the data can be organised and structured in reports to make sense of large amounts of data quickly. Reports can contain multiple pages, datasets, visual features and filters.
  • Dashboards: The summary or conclusion of the detailed report can be summarised on a single page Power BI dashboard.  
  • Tiles: A single block that holds the visualisation of any report. A single tile represents a single report.


3. Briefly Explain Some Components Of Power BI?

Power BI has the following essential components.

  • Power Query: This is used to extract and delete chunks of data from different data sources such as MySQL, SQL Server, and many others, usually when cleaning a data set.
  • Power Pivot: A data modelling engine that uses a functional language called Data Analysis Expression (DAX) to perform calculations. Also, it creates a relationship between various tables to be viewed as pivot tables.
  • Power View: This provides a simple, interactive overview of the datasets you are connected to. It allows you to extract data from each source easily. 
  • Power BI Desktop: Power BI Desktop is an aggregated tool that contains Power Query, Power View, and Power Pivot. It allows you to create advanced queries, data models, and reports using a desktop tool.
  • Power BI Mobile: This allows you to access reports and dashboards from a mobile device.
  • Power Map: This allows you to produce visuals using 3D geospatial data.
  • Power Q&A: To use natural language to ask questions, which Power BI then answers using the data available in the report.


4. Give An Overview Of The Different Licensing Options for Power BI

 There are three types of Power BI licences:

 1. Power BI Free: With this licence type only, the content in My Workspace is accessible

 2. Power BI Pro: Users with a Pro licence can share material with other workspaces, share their dashboard, subscribe to reports and other dashboards, and share with other Pro licence users.

Price: Charged for on a per user per month basis. Currently, $9.99 per user/month.

3. Power BI Premium:

There are two types of premium subscriptions:

a)      Per User: A Premium account provides accelerated data insights using advanced AI, simplifies data sharing and management at an enterprise level.

Price: Charged for on a per user per month basis. Currently, $20 per user/month

 b)     Per Capacity: An enterprise licence contains all the features of per user Premium licences but is licenced at an organisational level. It offers accelerated data insights, advanced AI and simplified data management and sharing across organisations.

Price: From $4,995 per month but depends on the capacity required.

For more details see: A Guide To Power BI Licences  and An Introduction To Machine Learning In Power BI

5. What Is DAX?

DAX allows you to make the most of your data sets and generate meaningful reports.

DAX is a functional programming language that includes conditional expressions, nested functions, value references, and other features. 

Numeric (integers, decimals, etc.) or non-numeric formulae are used (string, binary). An equal sign always precedes a DAX formula.

Technically, it is a library containing functions, constants, and operators that can out complex computations.

For more details see: Introduction To DAX In Power BI

6. Which Common Table Function In Power BI Is Used For Grouping Data?

One of the common functions used to group data in Power BI is “Group By”.

It is used to specify tables and group by columns instead of metrics. 


7. What Is Power Pivot?

Microsoft Excel’s 2010 add-on Power Pivot allows you to import millions of rows of data from different data sources into a single Excel worksheet. 

It allows you to connect different data sets, generate calculated columns and measures with formulae, and create Pivot Tables and Pivot Charts. 

For more details see: A Beginners Guide To Power Pivot & Power BI


8. Where Is The Data Stored In Power BI?

Power BI includes two primary data storage sources:

  1. Users upload data to Azure Blob Storage, where it is stored.
  2. All metadata and system records are saved in the Azure SQL Database.


9. What Is The Difference Between Power BI And Tableau?

The following are the main differences between Power BI and Tableau:

  1. Tableau utilises MDX to calculate table columns, whereas Power BI uses DAX.
  2. Tableau can handle vast amounts of data, whereas Power BI can only manage a limited data volume. 
  3. Overall, Tableau is more challenging to master than Power BI as it has a less straightforward interface. 

For a complete comparison, see Power BI vs Tableau. 


10. What Are Filters In Power BI?

Filters sort data according to the condition/s that has been applied to it. 

Filters allow you to choose specific fields and extract data at the page, visualisation, or report level. 

For example, if you have a multi-year international dataset, you could use filters to find Indian sales for the year 2019. 

Power BI can adjust and produce graphs or graphics depending on the conditions you apply to your filters. 

The types of filters available in Power BI are:

1. Page-level filters: 

These are applied on a particular page from various pages available within a report.

2. Visualisation-level filters: 

These are applied to both data and calculation conditions for particular visualisations.

3. Report-level filters: 

These are applied to the entire report.


11. List Out Some Drawbacks/Limitations Of Using Power BI.

The key limitations of Power BI are:

1 . It won’t accept files larger than 1 GB, and it won’t mix imported data with data accessible through real-time connections.

2. Just a handful of data sources allow real-time connections for Power BI reports and dashboards.

3. Dashboards do not take or pass parameters for users, accounts, or other entities.

4. It can be slow if it is not set up efficiently. See this article on- speeding up Power BI.


12. What Is A Power BI Personal Gateway, And Why Is It Useful?

A Power BI personal gateway creates a connection between your data store physically located onsite, such as laptop, desktop, or a server, and your online database. 

It uses the Azure service bus to create a bus connection between the two data stores. 

It is installed like a simple application or service and allows you to refresh your online database quickly and easily.

The term ‘personal’ in its name does not imply that businesses cannot use this service. It is used to differentiate it from other kinds of data management gateway.


13. Name The Different Connectivity Modes Available In Power BI?

In Power BI, there are three major connectivity modes:

1. SQL Server Import: 

Power BI makes it simple to connect to SQL Server data and execute queries. This is Power BI’s default and most popular connection option. It allows users to fully leverage Power BI Desktop’s capabilities by using a SQL Server Import.

2. Direct Query: 

Direct queries can be used on datasets that are larger than the suggested size. In this case, Power BI will simply save the source’s information and run direct queries against it. It does, however, restrict the procedures you can use to prepare your data for reporting.

3. Live Data Sources: 

SQL Server Analysis Services, Power BI datasets hosted by Power BI Service, and Azure Analysis Service can all be used to connect to live data sources using Power BI Service. All interactions on a live connection will be done through direct inquiries.

In addition you can manually import files either individually from your desktop or multiple files from a single folder.


14. What Are The Different Types Of Refresh Options Available In Power BI?

In Power BI, there are three different refresh options:  

1. Package Refresh: This synchronises data in Power BI Desktop or Excel files between Power BI, SharePoint Online, and OneDrive.

2. Tile Refresh: This feature refreshes the cache for Power BI tiles on dashboards every 15 minutes.

Once your data has been updated, you can use the third method. 

3. Visual Container Refresh: This refreshes the visual containers and visuals.


15. What Is Power BI Designer?

Power BI Designer is free of cost desktop software that brings the most widely used Power BI tools including Power Query, Power Pivot, Power View, and Power Map under one roof.

Power BI is used to integrate and model your data, as well as generate and publish reports and dashboards.

It’s a standalone Windows Desktop software that you may get from the Power BI website. 

This application integrates Power Query, Power Pivot Data Model, and Power View into a unified platform that allows clients to work on Power BI components offline before uploading them to the Power BI Service.


16. Which In-Memory Analytics Engine Does Power Pivot Use?

Velocity is Power Pivot’s core in-memory analytics engine.

Because it stores data in columnar databases, this engine can manage enormous quantities of data. Because all data is put into RAM in in-memory analytics, processing is extremely fast.


Final Thoughts

Good luck! Data people are generally friendly types so hopefully, it will be fun whether you get the job of not.

One last thought for you. Power BI is changing rapidly with updates coming out every month. It’s worth subscribing here to stay on top of the newest visuals and other updates to Power BI.

About Ben Richardson

Ben is a director of Acuity Training which he has been running for over 10 years.

He is a Natural Sciences graduate from the University of Cambridge and a qualified accountant with the ICAEW.

He previously worked as a venture capitalist and banker and so had extensive experience with Excel from building financial models before moving to learn SQL, Microsoft Power BI and other technologies more recently.