Most Important Interview Questions in Data Visualization

data visualization interview

This blog will feature the most important interview questions in data visualization associated with Power BI that gets you to stay ahead to crack the business intelligence interviews. 

But, why focus on Power BI? Well, not just being an Industry leader, Power BI is a popular cloud-based business analytics service that is easy to learn, collaborate & connect our data. 

Power BI is a Microsoft-launched super-flexible tool that enables anyone to visualize & analyze data, with better speed & efficiency. Remarkably, Power BI was identified as the leading BI software of 2021 with a commanding 36% of the market share (According to a research analysis by TrustRadius). Hence, a solid grip on PowerBI concepts & these most important interview questions in Data Visualization will come in handy for you.

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Important Interview Questions in Data Visualization(Power BI)

These important interview questions in Data Visualization cover the basics of Power BI that additionally helps to boost your business intelligence skills.

1. What are some data sources that Power BI can connect with?

The File category provides the following data connections:

Excel Workbook







SharePoint folder

The Database category provides the following data connections:

SQL Server database

Access database

SQL Server Analysis Services database

Oracle database

IBM Db2 database

IBM Informix database (Beta)

IBM Netezza

MySQL database

& more…

2. Explain Power BI Gateway.

  1. The gateway creates the connection between Power BI cloud-based data analysis technology and the data source located on-premises. And, this gateway is an application that can be installed on any server in the local domain. It is responsible for creating the connection and passing data through.

3. What is incremental refresh?

When we load data from the source into the destination (Power BI), there are two methods: Full Load, or Incremental Refresh. Here, ‘Full Load’ means fetching the entire dataset each time and wiping out the previous data. When we say the entire dataset, It means after all Power Query transformations, just because there might be some filtering in Power Query, whatever data that loads into the Power BI dataset in this sentence is considered as the entire data.

And, If the dataset is small, or the refresh process is not taking a long time, then the full load is not a problem at all. Also, the problem happens when either the dataset is big, or the refresh process takes longer than an acceptable timeframe. 

Now, Consider you have a large dataset including 20 years of data. From such a dataset, probably the data of 20 years ago, won’t change at all anymore, or even the data for 5 years ago, sometimes even a year ago. So why re-processing it again? why re-loading data that doesn’t update? Incremental Refresh is the process of loading only part of the data that might change, and adding it to the previous dataset which is not changing anymore.

4. Explain configuring Row-level security in PowerBI.

Row-level Security (RLS) with Power BI can be used to restrict data access for given users. Filters restrict data access at the row level, and you can define filters within roles. In the Power BI service, members of a workspace have access to datasets in the workspace. RLS doesn’t restrict this data access.

5. List some common DAX functions in Power BI.

  • SUM () 
  • SUMX () 
  • AVERAGE () 
  • MIN () 
  • MAX()

6. What is Query Folding?

Query folding is the ability of a Power Query(data transformation & data preparation engine) to generate a single query statement to retrieve and transform source data. Power Query engine makes solving common data tasks easy. A lot of precious time is usually spent on repetitive manual work such as cut & paste tasks or combining columns and applying filters. 

7. Explain the type of filters in Power BI.

Visual filter: It applies to a single visual on a report page. These are the annual filters that we can use in our data. Also, they work with the content of both page-level filters and reporting levels, which means the visual-level filters cannot be edited further to filter data in other visuals.

Page filter: It filters all the visuals on the report page of Power BI Report. This filter can be applied based on some conditions on a particular page within a given report.

Report filter: It applies to all pages in the report. These filters are the ones that affect all data in this report, no matter what we are looking for. It acts as a Global filter.

Drillthrough filter: With this filter, we create a destination report page that focuses on a specific entity, such as a supplier. From the other Power BI report pages, users can right-click a data point for that entity and drill through to the focused page.

8. Difference between slicer & filter.

Slicers are more user-friendly when compared to Filters. Also, Slicers are better when the number of values is limited as having a large number of values impacts the performance. While filters are better for a large number of values as it has more advanced selection options.

9. Which chart is used to compare target and actual value in Power BI?

Gauge Visual Chart

10. What is a Power map?

A power map will enable you to discover insights you might not see in traditional two-dimensional (2-D) tables and charts. With Power Map, you can plot geographic and temporal data on a 3-D globe or custom map, show it over time, and create visual tours you can share with others.

11. Difference between Self-service BI and Managed Enterprise BI.

Self-service BIManaged Enterprise BI
Data Analysis is EasyAnalyzing data gets a bit complex (time constraints & lack of information)
Companies are able to ingest data seamlessly from any data sourceNo specific order to ingest/manage the data, and data flows from many sources
No need of complex code execution, while users can generate actionable & insightful dashboards in no time.Generation of reports needs complex programming skills
Companies can easily process data & run business operations as the data ingestion is inline.Companies find this less effective to run the business operations as they cannot report, & analyse data/collaborate valuable insights from it.
Table: Self-service BI (vs) Managed Enterprise BI

12. Explain about creating and managing relationships on the Power BI desktop?

You can manage how Power BI treats and automatically adjusts relationships in your reports and models. To specify how Power BI handles relationship options, select File > Options and settings > Options from Power BI Desktop, and then select Data Load in the left pane. The options for Relationships appear.

13. What is the difference between Power BI Personal Gateway & Data Management Gateway?

Both gateways are free to use. The difference is the way that you want to use the gateway. The personal mode is mainly used for one-person use, not for the team. On-premises gateway, on the other hand, is a choice when you want to work in a collaborative environment.

14. How do you create a group in Power BI?

For creating a group of visuals in Power BI Desktop, select the first visual from the canvas, then hold the CTRL button. Then, Click one or more additional visuals that you want in the group. In the Format menu, select Group, and from the submenu select Group. Groups are displayed in the Selection pane.

These days, the domains like -Business intelligence & Business Analytics have evolved the decision-making skills of companies. This further helps them to make the best future actions for companies & result in growing more. Power BI stands tall as the popular leading tool in business analytics, digital marketing & data visualization.
Future proof your career with solid Data Visualization skills through ZEN Class-Career Programs offering 100% Job Placement Support in Business Analytics & Digital Marketing.

We’re working on the most important interview questions in Data Visualization – Part 3 (based on SQL). Stay Tuned!

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Lahari Chandana
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