Tableau Interview Questions and Answers

What is TABLEAU?

Tableau is a simple yet powerful tool used for Data Visualization in the business intelligence industry. Using tableau you can simplify raw data into an easily understandable format. The visualizations created by the tableau are in the form of Dashboards and Worksheets.

What are the file size limitations with Tableau?

In Tableau, there are no limitations with the file sizes. And moreover, there is no row or column limit to import the data.

Define LOD Expression?

LOD Expression stands for Level of Detail Expression, and it is used to run complex queries involving many dimensions at the data sourcing level.

Explain Tableau My Repository?

My Tableau repository is used to store Tableau Desktop version files, also includes various folders such as Bookmarks, Connectors, Data Sources, Extensions, Logs, Map Sources, Services, Shapes, TabOnlineSyncClient, and Workbooks.

My Tableau repository is usually located in the file path C:\Users\User\Documents\My Tableau Repository.

What is the Tableau Data Relationship?

A data relationship in Tableau is a flexible way of combining data from multiple tables or sheets for analysis in tableau.

Explain Join Operation in Tableau?

Combining data from two or more tables to a single table by using joining conditions. The joining operation is very common in data analysis, you may need to join the data from multiple sources, the Tableau provides the join feature to join tables present in the tableau. You can join up to 32 tables present in the data source.

Explain union Operation in Tableau?

The union is a method for combining data by appending rows of one table onto another table. For example, you might want to add new transactions in one table to a list of past transactions in another table.

Make sure the tables you union have the same number of fields, the same field names, and the fields are the same data type.

Wha t is Data Sorting in Tableau?

Data sorting is the process of arranging the given data in a systematic way based on your requirements.

The data present in the visualization and worksheet can be sort based on the requirement. It can sort the data based on data source order, ascending, descending, or depend on any measured value.

What is Tableau Worksheet?

A worksheet is a blank area, you can use to create views for the data analysis. Tableau provides the three blank default worksheets to establish a connection to your saved data source.

You can go ahead and add multiple worksheets to look at different data views on the same screen, one after another. Below is the image of the default worksheet.

What is Tableau Dashboard?

A dashboard is a combined display of multiple worksheets and related information in a single place. The dashboards are used to monitor and compare a variety of data simultaneously. The different data views are displayed all at once.

Explain Tableau Operator?

Tableau operators are symbols that tell the compiler to perform different types of mathematical and logical operations. Tableau provides a number of operators that are used to create calculated fields and formulas. General Operators helps to perform Mathematical, Logical, and Relational operations.

List out Tableau Functions?

Following are the functions available in Tableau :

  • Number Functions.
  • String Functions.
  • Date Functions.
  • Type Conversion.
  • Logical Functions.
  • Aggregate Functions.
  • User Functions.

The Heat map is a graphical representation of data where values are depicted by color. Heat maps make it easy to visualize complex data and understand it at a glance

List out Tableau File Extensions.

The Tableau file extensions are:

  • Tableau Workbook (.twb)
  • Tableau Data extract (.tde)
  • Tableau Datasource (.tds)
  • Tableau Packaged Datasource (.tdsx)
  • Tableau Bookmark (.tbm)
  • Tableau Map Source (.tms)
  • Tableau Packaged Workbook (.twbx) – zip file containing .twb and external files.
  • Tableau Preferences (.tps)
What is the latest version of Tableau Desktop?

Tableau Desktop's latest version is 2019.1(as of Feb, 14th 2019).

What is TreeMap?

The Treemap displays data in nested rectangles. The dimension values define the structure of the Treemap and measure values define the size or color of the individual rectangle. The rectangles are easy to visualize as both the size and shade of the color of the rectangle reflect the value of the measure.

What is the difference between a Heat map and Treemap?

TreeMap

Heat Map

  • The TreeMap displays the data hierarchically and shows them as a set of nested rectangles.
  • The Heat Map represents the data graphically which uses multiple colors to represent different values.
  • Colors and size of rectangles are respective to the values of the data points
  • The data will be represented in dark color.
  • It is used for comparing the categories with colors, size, and it can also be used for illustrating the hierarchical data and part to whole relationships.
  • It is used for comparing the categories based on color and size. And also it is great for spotting the patterns based on the density of the information.
What is a Histogram Chart?

A histogram chart in Tableau represents the frequencies of values of a variable bucketed into ranges. A Histogram is similar to a bar chart but it groups the values into continuous ranges. Each bar in the histogram represents the height of the number of values present in that range.

What is a parameter Tableau? And how it works?

Parameters are dynamic values, we can replace the constant values in calculations.

What is Tableau Metadata?

Metadata is data, that provides information about other data. In other words, it is data about data. Tableau facilitates in capturing the information details of the sources like columns and their information sorts. Information is employed to form dimensions, measures, and also the fields square measure calculated.

What are the different operations we can perform on Metadata?
  • Hide and Unhide the Metadata in Tableau
  • Rename Metadata fields in Tableau
  • Create a hierarchy of fields in Tableau
  • Create a folder in Tableau
  • Create Calculated fields in the Tableau
What is Tableau Hierarchy?

Hierarchies are a logical arrangement of relevant unique attributes in a data set. Hierarchies arrange data fields in a level, for instance, a Geography hierarchy would have a region, country, state, city, area levels. Or, a Time hierarchy has a year, month, week, day as its levels.

What is the Tableau Storyline?

Tableau story is a sequence of visualizations that work together to convey information. Stories can be used to narrate data, provide content, and also how to demonstrate decisions related to outcomes or simply make a strong case.

What are operations can be performed on the Tableau Story Line?
  • Create a Story Point in Tableau
  • Create a New Story Point in Tableau
  • Create Duplicate Story Point in Tableau
  • Add Text to a Story in Tableau
  • Display Size of the Story Point in Tableau
  • Format Tableau Story Layout
  • Remove a Story Point from Tableau
What are the different data types in Tableau?

Tableau supports the below data types.

Data Type

Meaning

Examples

String Data Type

  • A string is a data type that contains zero or more characteristics in the text format, and the value will be considered as a string when it is encoded in single or double-quotes are called string data types.

Example: "Apple", 'Orange'.

Numeric Data Type

  • If a data value present in the data type contains only numbers in them, then this kind of data type is called numeric data types, the data values can be either an integer type or floating type.

Example: A=222, N=455.00=455

Boolean Data Type

  • The boolean data type values are a result of relational calculations. Therefore, True and False boolean values are known as logical values.

Example: If A=4 and B=8, A>B=False.

Date and Date and Time Data Type

  • The data value present in the data type contains data in the date and time format then the data type is called a date-time data type.
Example: #20 January 2020

Geographic Data Types

  • The geographic data types are the data values that are used in a map. Values such as country name, state name, city, region, postal codes, etc. belong to the geographic data type. The fields of this data type are denoted by a globe icon.

Example: India, Italy, Canada

Explain different connection types in Tableau?

There are 2 connection types available in Tableau.

  • Extract : Extract is a snapshot of data that will be extracted from the data source and put into the Tableau repository. This snapshot can be refreshed periodically fully or incrementally. This can be scheduled in Tableau Server.
  • Live : It creates a direct connection to the data source and data will be fetched directly from tables. So, data will be up to date and consistent. But, this also affects access speed.
What is Tableau Forecasting?

Forecasting is a process of predicting the future value of the measure. We are going to use regular patterns in the measured value to predict future trends.

What is Tableau Filter, Mention Different Kinds?

You can use filters in the Tableau worksheet to restrict the number of records present in the dataset. Depending on your requirements you can use different types of filters as given below.

  1. Extract Filters : This filter is used to filtering the extracted data from the data source.
  2. Data Source Filters: It is used to filter the data at the data source level. It can restrict the records present in the data set.
  3. Context Filters: This filter is an independent filter that can create a separate dataset out of the original data set
  4. Dimension Filters: This filter is used to filter the dimension variable from the worksheet.
  5. Measure Filters: This filter is used to filter the Measure variable from the worksheet.
  6. Date Filter: Date filters used to filter dates from the date field.
What is Context Filter in Tableau?

A Context filter is an independent filter that can create a separate dataset out of the original data set and compute the selections made in the worksheet.

One or more category filter that separates the dataset into major parts can be used as a context filter.

What is the Dimension Filter in Tableau?

When a dimension is used to filter the data in the worksheet, it is called a dimension filter. Using this filter, you can include or exclude the members in the dimension.

What is Tableau Measure Filter?

You can use a measure filter to filter the data based on the values present in a measure. The aggregated measure values can be used in the measure filter to modify the data.

What is the Tableau Trend line?

A trend line is a line showing the patterns or trends emerging from data points. Trend lines help us in interpreting data trends, predicting future scenarios, and draw a correlation between two variables in the analysis.

What is trend line assumptions?
  • The model is a functional simplification of the true data generating process and is very accurate.
  • All the errors average to zero. Also, the errors are uncorrelated with the independent variable.
  • The errors have constant variance and they are not correlated with each other.
  • The explanatory variables are not exactly linear functions of each other.
What is an exponential trend line?

Exponential trend lines are curved lines that are suitable when the rate of change between variables rises at an increasingly higher level.

What is Tableau Aggregation?

In Tableau, the aggregate function allows you to summarize your data, an aggregation performs a calculation on the set/group of values and returns the single value.

Is the list Aggregation function available in Tableau?
  • AVG() Function: This function returns the average of all the values in the expression. AVG can be used with numeric fields only. Null values are ignored.
  • ATTR() Function: This function returns the value of the expression if it has a single value for all rows. Otherwise returns an asterisk(*). Null values are ignored.
  • SUM() Function: This function returns the sum of all values in the given expression. SUM can be used with numeric fields only. Null values are ignored.
  • MIN() Function: This function returns the minimum of an expression across all records. If the expression is a string value, this function returns the first value where the first is defined by alphabetical order.
  • MAX() Function: This function returns the maximum of an expression across all records. If the expression is a string value, this function returns the last value where last is defined by alphabetical order.
  • VAR() Function : This function returns the statistical variance of all values in the given expression based on the given sample.
  • VARP() Function: This function returns the statistical variance of all values in the given expression on the entire given sample.
  • STDEV() Function : This function returns the statistical standard deviation of all values in the given expression based on a given sample.
  • STDEVP() Function: This function returns the statistical standard deviation of all values in the given expression based on a biased population.
  • COUNT() Function: This function returns the number of items in a group. Null values are not counted.
  • COUNTD() Function : This function returns the number of distinct items in a group. Null values are not counted.
  • COLLECT() Function: An aggregate calculation that combines the values in the argument field. Null values are ignored.
  • CORR() Function: Returns the Pearson correlation coefficient of two expressions.
  • COVAR() Function: Returns the sample covariance of two expressions.
  • COVARP() Function: Returns the population covariance of two expressions.
  • MEDIAN() Function: Returns the median of an expression across all records. Median can only be used with numeric fields. Null values are ignored. This function is not available for workbooks created before Tableau Desktop 8.2 or that use legacy connections.
  • PERCENTILE() Function: Returns the percentile value from the given expression corresponding to the specified number. The number must be between 0 and 1 (inclusive)—for example, 0.66, and must be a numeric constant.
What is Tableau Dimension Variable?

Dimension is a parameter that contains qualitative values, You can use dimensions to categorize, segment, and reveal the details in your data.

Example : Category, City, Country, Customer ID, Customer Name, Order Date, Order ID

What is Tableau Measure Variable?

The measure is a parameter that contains quantitative values, that you can measure, the measure values cannot be aggregated.

Example : Profit, Quantity, Rank, Sales, Sales per Customer, Total Orders.

Explain inner join with an example?

Inner Join :

  • It will join all the common records between the two tables or sheets.
  • The joining condition will be given based on the primary key( The PRIMARY KEY constraint uniquely identifies each record in a table)
  • One or more joining conditions can be specified to join the tables.
  • Many tables can be joined together in Tableau for visualization.

Example : Consider there are two tables TableA and TableB containing customer details and another one is containing Employee details as below.

TableA

Customer Gender Age
Adam Male 24
Jhon Male 32
Jack Male 29
Nick Male 37
Susan Female 31

TableB

Employee Title Wage
Jack Clerk 17$/hr
Jhony Clerk 19$/hr
Mary Mngr 20$/hr
Susan Mngr 19$/hr
  • If you compare two tables(TableA and TableB), you can see that Jack and Susan are both at the customer table as well as the employee table.
  • The Inner join selects the common names from two tables and intersects each other and the rest of the rows are discarded.
  • The resultant table will look like as below.
Customer Gender Age Employee Title Wage
Jack Male 29 Jack Clerk 17$/hr
Susan Female 31 Susan Mngr 19$/hr

The Ven diagram for inner join: inner-joining-operation-tableau

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