Most Important Interview Questions in Data Visualization [Part-2]

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.

Important Interview Questions in Data Visualization(Power BI)

These important interview questions in Data Visualization cover the basics of Power BI that additionally help 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

Text/CSV

XML

JSON

Folder

PDF

Parquet

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…

Before we move to the next part, you should have a deeper knowledge of data engineering concepts. You can consider enrolling yourself in GUVI’s Data Engineering Career Program, which lets you gain practical experience by developing real-world projects and covers technologies including data cleaning, data visualization, Infrastructure as code, database, shell script, orchestration, cloud services, and many more.

Additionally, if you would like to explore Data Engineering and Big Data through a Self-paced course, try GUVI’s Data Engineering and Big Data self-paced course.

2. Explain Power BI Gateway.

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 from 20 years ago, won’t change at all anymore, or even the data from 5 years ago, sometimes even a year ago. So why re-process 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 () 
• AVERAGEX() 
• 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-and-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 the 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. 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.

12. Explain 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.

Kickstart your career by enrolling in GUVI’s Data Engineering Career Program where you will master technologies like data cleaning, data visualization, Infrastructure as code, database, shell script, orchestration, and cloud services, and build interesting real-life cloud computing projects.

Alternatively, if you want to explore Data Engineering and Big Data through a Self-paced course, try GUVI’s Data Engineering and Big Data Self-Paced course.

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