1. What is Tableau?

Answer:
Tableau is a powerful data visualization tool used for data analysis and reporting. It allows users to connect to multiple data sources, visualize the data, and generate interactive reports and dashboards. Tableau provides both desktop and server-based solutions.

2. What are the different Tableau products?

Answer:
Tableau offers several products:

• Tableau Desktop: Used for individual analysis and creating reports and dashboards.
• Tableau Server: Allows sharing of Tableau workbooks and dashboards across an organization.
• Tableau Online: Cloud-based version of Tableau Server.
• Tableau Public: Free version to publish and share Tableau visualizations publicly.
• Tableau Prep: A data preparation tool for cleaning, reshaping, and transforming data before analysis.

3. What is the difference between Tableau Desktop and Tableau Server?

Answer:
Tableau Desktop is for creating visualizations and reports locally on your machine, while Tableau Server is used for sharing, collaborating, and managing these visualizations in a centralized server environment across an organization.

4. What is the role of a data source in Tableau?

Answer:
A data source in Tableau refers to the dataset you connect to for analysis. It defines the data structure and fields that will be used in creating visualizations. Data can be imported from various sources such as Excel, SQL, Google Analytics, etc.

5. What are calculated fields in Tableau?

Answer:
Calculated fields in Tableau are custom fields created using formulas, functions, and expressions. These fields allow you to perform operations on existing data, like aggregating, filtering, or applying mathematical operations.

6. What is a Tableau dashboard?

Answer:
A Tableau dashboard is a collection of visualizations (worksheets) that are presented together on a single screen. Dashboards enable a more interactive and holistic view of data and are used to present data insights to end users.

7. Explain the different types of joins in Tableau.

Answer:
Tableau supports four types of joins:

• Inner Join: Returns only the matching rows from both tables.
• Left Join: Returns all records from the left table and matching records from the right table.
• Right Join: Returns all records from the right table and matching records from the left table.
• Full Outer Join: Returns all records when there is a match in either the left or right table.

8. What is the difference between a live connection and an extract in Tableau?

Answer:

• Live connection: Data is queried in real-time from the original source.
• Extract: A snapshot of the data is created and stored locally, improving performance for large datasets.

9. What is Tableau Prep?

Answer:
Tableau Prep is a data preparation tool that allows you to clean, combine, and reshape data before analyzing it in Tableau. It provides a visual interface for transforming data into a usable format.

10. What is a story in Tableau?

Answer:
A story in Tableau is a sequence of sheets or dashboards that work together to convey a specific insight or narrative. It can include multiple views and captions, guiding the user through data exploration.

11. What are context filters in Tableau?

Answer:
Context filters are used to set a filter context for other filters. They can improve performance and solve issues when multiple filters are applied, by acting as an independent filter set for others to depend on.

12. Explain the difference between discrete and continuous fields in Tableau.

Answer:

• Discrete fields: Represent distinct values (e.g., category names, states). They create headers or axes.
• Continuous fields: Represent a range of values (e.g., sales, dates). They generate axes with continuous scales.

13. How do you improve the performance of a Tableau workbook?

Answer:

• Use extracts instead of live connections when possible.
• Optimize calculations and filters.
• Reduce the complexity of the data model.
• Minimize the use of large data sources and unnecessary fields.

14. What is the purpose of the “Data Blending” feature in Tableau?

Answer:
Data blending allows combining data from different data sources. It is used when combining data that doesn’t share a common connection but needs to be visualized together, such as blending data from different databases.

15. What is a dimension in Tableau?

Answer:
A dimension in Tableau is a qualitative field, such as categories or attributes, that typically describes data (e.g., country, product name, date). Dimensions are used to segment and slice data.

16. What is a measure in Tableau?

Answer:
A measure is a quantitative field that can be aggregated (e.g., sum, average, count). Examples include sales, profit, quantity, etc.

17. What is a filter in Tableau, and how does it work?

Answer:
A filter in Tableau is used to restrict the data displayed in a view based on certain conditions. Filters can be applied to dimensions, measures, or date fields to control which data points are shown.

18. Explain the difference between table calculation and calculated field in Tableau.

Answer:

• Table calculation: A type of calculation that is performed on the data after it has been retrieved and visualized. It operates at the level of the table or view, such as ranking, percent of total, etc.
• Calculated field: A custom field created using a formula or expression applied before the data is rendered in the view.

19. What is a heat map in Tableau?

Answer:
A heat map is a data visualization that uses colors to represent values in a matrix format. It helps in identifying patterns or correlations in large datasets.

20. What is the purpose of the “ROW_NUMBER()” function in Tableau?

Answer:
The ROW_NUMBER() function is used to assign a unique number to each row in a result set based on the specified order. It is often used in ranking data.

21. What are the different chart types available in Tableau?

Answer:
Tableau supports various chart types such as bar charts, line charts, scatter plots, pie charts, area charts, heat maps, histograms, box plots, treemaps, and more.

22. What is an LOD (Level of Detail) expression in Tableau?

Answer:
LOD expressions allow users to control the granularity at which calculations are performed. They provide three types of expressions:

• Fixed: Calculates the measure at a fixed dimension level.
• Include: Adds additional dimensions to the calculation.
• Exclude: Excludes dimensions from the calculation.

23. What is the purpose of blending data in Tableau?

Answer:
Data blending is used when you need to combine data from different sources that do not have a common key. It allows you to aggregate data from multiple sources into a single view.

24. Explain the concept of actions in Tableau.

Answer:
Actions in Tableau are interactive elements that allow users to interact with data. They can be filters, highlights, or URL actions that trigger different behaviors in the dashboard.

25. What is the purpose of the “Show Me” feature in Tableau?

Answer:
The “Show Me” feature in Tableau provides a selection of visualization types that are appropriate for the data you’ve selected. It helps guide users in choosing the best chart for their analysis.

26. How do you handle null values in Tableau?

Answer:
Tableau offers various methods for handling null values, such as:

• Using calculated fields to replace nulls with a default value.
• Filtering out null values.
• Displaying null values as a specific category or color in visualizations.

27. How can you share Tableau workbooks with others?

Answer:
You can share Tableau workbooks by publishing them to Tableau Server or Tableau Online, exporting them as PDF or images, or by sharing the workbook file (.twb or .twbx).

28. Explain the concept of a dual-axis chart in Tableau.

Answer:
A dual-axis chart is a visualization that allows you to plot two different measures on the same graph but with two different y-axes, typically for comparing two different types of data with different units of measure.

29. What is the difference between a filter and a parameter in Tableau?

Answer:

• Filter: Restricts the data displayed based on selected values.
• Parameter: A dynamic input value that can be used in calculations or to control filters, allowing users to interactively change the behavior of the dashboard.

30. What is Tableau’s data security model?

Answer:
Tableau provides several data security mechanisms, including:

• Row-level security: Ensures users only see data that they have access to, based on user roles or group membership.
• Authentication: Tableau supports different authentication methods such as SSO, Active Directory, etc.