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Data Visualization

Tableau Interview Questions and Answers

What is Tableau?

Tableau is a business intelligence (BI) and visualization tool that can help you create beautiful and visually-appealing reports, charts, graphs and dashboards using your data.

What is the latest version of Tableau Desktop?

Tableau Desktop 2020.2  (as of May, 2020)

What is data visualization?

Data visualization is the graphical representation of information and data. It is communication of data in visual manner and turning the raw data into insights that can be easily interpreted by the end users.

What are the five main products offered by Tableau?

Tableau offers the below mentioned five main products:

  • Tableau Desktop
  • Tableau Server
  • Tableau Online
  • Tableau Public
  • Tableau Reader

What are Filters in Tableau?

A Filter is used to show only the necessary data, it shows the exact data we want. There are three types of Filters in Tableau:

  • Quick Filter
  • Context Filter
  • Normal Filter

What are the different filters in Tableau and how are they different from each other?

The different filters in Tableau are: Quick , Context and Normal filter:

  • Normal Filter is used to restrict the data from database based on selected dimension or measure. A Traditional Filter can be created by simply dragging a field onto the ‘Filters’ shelf.
  • Quick filter is used to view the filtering options and filter each worksheet on a dashboard while changing the values dynamically (within the range defined) during the run time.
  • Context Filter is used to filter the data that is transferred to each individual worksheet. When a worksheet queries the data source, it creates a temporary, flat table that is uses to compute the chart. This temporary table includes all values that are not filtered out by either the Custom SQL or the Context Filter.

How is the Context Filter different from other Filters?

  • Whenever we create a Context Filter, Tableau will create a temporary table for this particular Filter set and other Filters will be applied on the Context Filter data like cascade parameters.
  • Suppose, we have created a Context Filter on countries, USA and India, Tableau will create a temporary table for these two countries’ data and if we have any other Filters other will be applied on these two countries’ data if we don’t have any Context Filter, each record will check for all Filters.

What is the difference between the quick filter and the normal filter in Tableau?

Quick filter is used to view the filtering options and can be used to select options. Whereas, the Normal filer is something with which we can limit the options from the list or use some conditions to limit the data by field or value.

How to remove the Show all option from a Tableau Auto Filter?

Follow the steps to remove Show All option from a Tableau auto filter:

Right-click on Filter > Customize > uncheck the “Show All” option

What are Measures and Dimensions?

Measures, as its name says, are those fields that can be measured, or aggregated, or used for mathematical operations. Measures are continuous or quantitative data.

Dimensions are the descriptive attribute values, defining multiple characteristics. Dimensions are categorical or qualitative data.

What are the different types of joins in Tableau?

In general, there are four types of joins in Tableau: inner join, left join, right join and full outer join.

What is the difference between joining and blending in Tableau?

Joining the data can be done when the data comes from the same source, for example from multiple sheets tabs from a single excel file.

If that same information was stored in separate excel files you will need to do a data blending in Tableau. A blend is always required if the data is stored in two separate “data sources” within Tableau. So even if your data is very closely related and exists in two separate files or databases, you will have to do a data blend if you are combining the data in Tableau.

Blending of data mix the data from the different data sources and allow the users to perform the analysis in a single sheet.

When blending data, the first data source used in your view will dictate how your worksheet view in Tableau is built. The secondary (blended) data source will be able to contribute extra information, but will not be able to change the overall structure of the view. The secondary data source’s values can be aggregated and applied to the existing view after you have established a “relationship” by assigning a variable that both the primary and secondary data sources have in common.

What are sets?

Sets are custom fields that define a subset of data based on some conditions. A set can be based on a computed condition, for example, a set may contain customers with sales over a certain threshold. Computed sets update as your data changes. Alternatively, a set can be based on specific data point in your view.

What are groups?

A group is a combination of dimension members that make higher level categories. For example, if you are working with a view that shows average test scores by major, you may want to group certain majors together to create major categories.

What is dual axes?

To display two measures in one graph, Tableau uses dual axes.

What is blended axis?

Blend axes for multiple measures into a single axis. Measures can share a single axis so that all the marks are shown in a single pane. To blend multiple measures, drag one measure or axis and drop it onto an existing axis.

What is the maximum number of tables we can join in Tableau?

We can join a maximum of 32 tables in Tableau.

What is the difference between a tree map and heat map?

A heat map can be used for comparing categories with color and size. With heat maps, you can compare two different measures together.

A tree map also does the same except it is considered a very powerful visualization as it can be used for illustrating hierarchical data and part-to-whole relationships.

What is the different between twb and twbx file extensions?

The file extension .twb is a live connection; it points to the data source. The user receiving .twb needs permission to access the said data source and no data is included.

On the other hand, .twbx takes the data offline and stores it as a package or zip-like file, thereby eradicating the need for permissions.

How to do Performance Testing in Tableau?

Performance testing is again an important part of implementing tableau. This can be done by loading Testing Tableau Server with TabJolt, which is a “Point and Run” load generator created to perform QA. While TabJolt is not supported by tableau directly, it has to be installed using other open source products.

What is aggregation and disaggregation of data?

The process of viewing numeric values or measures at higher and more summarized levels of the data is called aggregation. When you place a measure on a shelf, Tableau automatically aggregates the data, usually by summing it. You can easily determine the aggregation applied to a field because the function always appears in front of the field’s name when it is placed on a shelf. For example, Sales becomes SUM(Sales).  You can aggregate measures using Tableau only for relational data sources. Multidimensional data sources contain aggregated data only. In Tableau, multidimensional data sources are supported only in Windows.

According to Tableau, Disaggregating your data allows you to view every row of the data source which can be useful when you are analyzing measures that you may want to use both independently and dependently in the view. For example, you may be analyzing the results from a product satisfaction survey with the Age of participants along one axis. You can aggregate the Age field to determine the average age of participants or disaggregate the data to determine what age participants were most satisfied with the product.

Mention what are different Tableau files?

Different Tableau files include:

  • Workbooks: Workbooks hold one or more worksheets and dashboards
  • Bookmarks: It contains a single worksheet and its an easy way to quickly share your work
  • Packaged Workbooks: It contains a workbook along with any supporting local file data and background images
  • Data Extraction Files: Extract files are a local copy of a subset or entire data source
  • Data Connection Files: It’s a small XML file with various connection information

What is data modeling?

Data modeling is the analysis of data objects that are used in a business or other context and the identification of the relationships among these data objects. Data modeling is the first step in performing object-oriented programming.

Distinguish between Parameters and Filters.

  • Parameters are dynamic values that can replace constant values in calculations. Parameters can serve as Filters as well.
  • Filters, on the other hand, are used to restrict the data based on a condition that we have mentioned in the Filters shelf.

What is Page shelf?

Page shelf is a powerful part of Tableau that we can use to control the display of the output and the printed results of the output.

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