power bi qa

Power BI Q&A

Questions & Answers on using Power BI

We put together a list of Power BI QA’s. If you don’t find your answer on using Microsoft Power BI here, you can always contact us. Managing data can be quite challenging, and accuracy of your data cannot be compromised. To help you we have professional support available in Dutch, English, Estonian & French. View our support formulas and get in contact.

Q: What is Power BI?

Power BI is a business intelligence and data visualization tool developed by Microsoft. It is designed to help organizations and individuals transform data into actionable insights through interactive reports and dashboards. Power BI is part of the Microsoft Power Platform, which includes other tools like Power Apps for app development and Power Automate for workflow automation.

Data Visualization: Power BI allows users to connect to various data sources, including databases, spreadsheets, cloud services, and online data sources. You can then create interactive visualizations, such as charts, graphs, maps, and tables, to represent your data.

Data Transformation: You can clean and transform data within Power BI using its Power Query Editor. This feature helps you shape your data for analysis and reporting.

Data Modeling: Power BI provides a data modeling interface where you can create relationships between tables, define calculated columns and measures, and build data hierarchies.

Reports: Users can create interactive reports by dragging and dropping data fields onto a canvas, which can include multiple visualizations, filters, and slicers.

Dashboards: Dashboards are one-page collections of visuals and reports, designed for at-a-glance monitoring of key performance indicators (KPIs). You can pin visuals from different reports to a dashboard to create a consolidated view.

Sharing and Collaboration: Power BI allows you to publish and share your reports and dashboards with others within your organization. Users can access these reports through the Power BI service, or you can embed them in websites or applications.

Mobile Accessibility: Power BI provides mobile apps for iOS and Android, enabling users to access reports and dashboards on smartphones and tablets.

Integration: Power BI integrates with a wide range of Microsoft and third-party products and services, including Azure services, SharePoint, and various data connectors.

Security and Governance: Organizations can implement data security and governance measures to control access to data, ensure compliance, and track usage.

Within the analytics and BI platform market, Microsoft has been positioned as a leader in the 2023 Gartner Magic Quadrant for Analytics and Business Intelligence platforms.

Q: What is the difference between Power BI desktop, Power BI Service and Power BI Mobile?

The Power BI-suite consists of Power BI desktop, Power BI Service and Power BI Mobile.

Power BI Desktop is for report creation and authoring on Windows computers. It is a free, powerful business intelligence application developed by Microsoft. It is part of the broader Power BI suite. Power BI Desktop is primarily used for creating and designing interactive reports and data visualizations that can be shared with others through Power BI Service.

Power BI Service, also known as Power BI Online, is for publishing, sharing, and collaborating on reports and dashboards in the cloud.

Power BI Mobile is for accessing and interacting with Power BI content on mobile devices, such as smartphones and tablets. It enables users to stay connected to their data and make data-driven decisions while on the go.

Q: What is Power BI Report builder?

Power BI Report Builder is a separate and more traditional reporting tool that is part of the Microsoft Power BI ecosystem. It is designed for creating paginated (pixel-perfect) reports, such as operational and transactional reports that have strict formatting requirements and are typically used for printing or exporting to formats like PDF or Excel.

Q: What licenses are available for Power BI?

Microsoft’s licensing model dares to change from time to time. Therefore a redirect to the Microsoft site. If you have any further questions, you can always contact us. We are happy to help you select the best license for your situation.

Q: What is DAX?

DAX or Data Analysis Expression is the native formula and query language for Microsoft PowerPivot, Power BI Desktop and SQL Server Analysis Services (SSAS) Tabular models. It is a collection of functions, operators, and constants that can be used in a formula to calculate values. Simply said; DAX helps you compile new information based on data already in the model.

Q: What is de difference between Dax and Excel-formulas?

In Excel you refer to cells when creating formulas. e.g. SUM(B2:B9)
In Power BI using DAX, you refer to rows and columns – which basically means you refer to tables. e.g. TotalSalesAmount = SUM(Sales[[Sales Amount]])
Another significant difference is the usage of a Filter and Row Context when using DAX.

Q: What is the difference between a calculated column and a measure in DAX?

A calculated column:
– Is used to add a new column to a table in a data model
– It calculates a value for each row in the table
– Are physically stored in the data model, taking up memory and storage space
– Are often used for adding new attributes or intermediate calculations to your data that are needed for reporting , filtering, or creating relationships.

A measure:
– Is used to perform an aggregation or calculation on a specific set of data, typically across one or more tables.
– They do not store pre-calculated values in the data model. They are calculated on the fly when needed.
– Are essential for aggregating data and providing summarized information, such as sums, averages, counts, or ratios. They are used in visuals, pivot tables, and charts to show aggregated results

Q: What are the best practices for writing efficient DAX formulas?

Make sure measure and column names are user friendly.

Monitor Resource Usage: Use the Performance Analyzer and DAX Studio to monitor resource usage and identify performance bottlenecks.

Make your Dax easy to read. Dax formatter is free to use.  DAX Formatter by SQLBI

Use variables

Avoid complex IF-statements. Consider using other functions like ‘SWITCH’

Use Divide instead of /

Use ISBLANK() instead of = Blank() check


Use the DISTINCT() and VALUES() functions consistently
If Power BI detects a referential integrity violation, it fills the column with a blank value. Because it can’t check for violations when running direct queries, Microsoft Power Bi Tool adds a blank value to columns.
DISTINCT() and VALUES() are two different functions: Due to an integrity violation, DISTINCT() does not return any blanks added. A blank is only included in the DISTINCT() function if it is part of the original data.
VALUES(): Returns both original data blanks and blanks added by Power BI as a result of referential integrity violations.
Throughout the report, make sure to use the DISTINCT() and VALUES() functions consistently. Otherwise, the values for blank columns will be inconsistent.

Q: How can I troubleshoot DAX errors or issues in my calculations?

Errors are highlighted during development. A syntax error is displayed with a yellow warning symbol appearing below the DAX expression.

Check for syntax errors. Check for syntax errors in the formula, such as missing commas or parentheses.

Break complex DAX expressions into smaller, more manageable parts. This makes it easier to identify where the problem lies. You can do this by using variables. After RESULT you can put any variable to test

Test always with sample data. 

Q: What are context transition and filter context in DAX?

Context transition and filter context are important concepts that play a central role in evaluating calculations.

To properly understand context transition, it is important to understand row context, filter context and calculate. To understand context transition, watch the 4 videos below:
1. Row context in DAX
2. Filter context in DAX
3. Introducing Calculate in DAX
4. Understanding context transition in DAX

Q: What is data modeling in Power BI?

Data modeling is the process of analyzing and defining all the different data types your business collects and produces, as well as the relationships between those bits of data. By using text, symbols, and diagrams, data modeling concepts create visual representations of data as it’s captured, stored, and used at your business. As your business determines how data is used and when, the data modeling process becomes an exercise in understanding and clarifying your data requirements.

Q: What is a star schema and how can I create one in Power BI?

Star schema is a mature modeling approach widely adopted by relational data warehouses. It requires modelers to classify their model tables as either dimension or fact.

Dimension tables
 describe business entities—the things you model. Entities can include products, people, places, and concepts including time itself. The most consistent table you’ll find in a star schema is a date dimension table. A dimension table contains a key column (or columns) that acts as a unique identifier, and descriptive columns.

Fact tables
 store observations or events, and can be sales orders, stock balances, exchange rates, temperatures, etc. A fact table contains dimension key columns that relate to dimension tables, and numeric measure columns.
Here you find more about Dimensional Modeling Techniques.

Open Power BI Desktop: Launch the Power BI Desktop application on your computer.

Get Data: 
In Power BI Desktop, go to the “Home” tab on the ribbon at the top of the window.

Select Data Source: 
Click on the “Get Data” option. This will open a list of available data source options.

Choose a Data Source: 
Select the type of data source you want to connect to. Power BI supports various data sources, including Excel files, databases, online services, web sources, and more. Choose the one that matches your data source.

Connect to the Data Source: 
Depending on your selection, you’ll need to provide connection details. This might include a file path, server address, database credentials, URL, API key, or other relevant information. Enter the required information, and then click “Connect.”

Model view
: This is where you ‘ll design your data model the model view connect some of the tables.

You can find more information about different ways to create relationships and edit relationships here.

Power BI QA

Q: How can I optimize my data model for performance in Power BI?

Data source selection: Choose an appropriate data source that meets your needs. Importing data into Power BI is usually faster than using DirectQuery or Live Connection to external databases.

Open Power Query Editor and enable the data profiling tools. Remove unnecessary columns, filter out unwanted rows, and aggregate data at the source to reduce the amount of data loaded into Power BI.

Star schema: Use a star schema or a well-structured data model. In a star schema, you have a central fact table connected to dimension tables. This simplifies data relationships and reduces the need for complex DAX calculations.

Calculated columns vs. measures: Use calculated columns sparingly and prefer measures for dynamic calculations. Calculated columns are precomputed and can consume memory and processing power.

Summarize data: Avoid loading unnecessary detail in your data model. Summarize data to an appropriate level, especially when working with large datasets.

Use relationships wisely: Define relationships between tables carefully and avoid creating unnecessary relationships. Also, set the correct cardinality and cross-filtering behavior for each relationship.

Monitor performance: Use the Performance Analyzer and Query Diagnostics features in Power BI to identify performance bottlenecks.

Dax Studio: the best tool to analyze DAX queries in Power BI.

VertiPaq Analyzer

How to use Dax Studio and Vertipaq Analyzer.  The introduction video is for free

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