# Tableau Tips: Computing cross purchase

March 16, 2019

To be prepared to respond to these custom requests, as an analyst, you’ll need to have a rich resource of tips and tricks for quick solutions.

Therefore, in this article we explore a Tableau tip on answering the following question framed in three different ways.

We assume a scenario whereby product user’s demand to know;

• For the customers who purchased ‘Chairs’, which other products did they purchase? – Case of retail industry

• For the viewers who watched ‘BBC’, which other TV stations did they watch? – Case  of media industry

• For the users who visited ‘www.rigordatasolutions.com’, which other sites did they visit? – Case of online business

These are just out of the box questions but am sure in your daily tasks you’ll come across scenarios where this technique is appropriate.

Let’s build a case first

Using Superstores data set pre-packaged with Tableau app, we’ll demonstrate this by computing the number of customers who purchased a certain product Sub-Category, let’s say ‘chairs’ indicating the proportion of other products they purchased.

Once connected to the data set above;

Create a parameter field comprised of all Product Sub-Category’s

(Why do we create a parameter?- We need to make this calculation dynamic, enabling the end user select product Sub-Category of choice other than just ‘Chairs’)

Create our magical calculated field

The calculation is as follows;

Building our viz

Drag dimension field Sub-Category to the rows shelf

Drag the calculated field - Computed field - above to the Text shelf

Show the parameter control.

Formatting and editing we’ve;

With the help of the parameter control, user can quickly and easily adjust the view for insights.

Some of the insights from this viz could be as follows;

• Of the 319 customers who purchase chairs, 276 and 262 purchased Binders and Papers respectively, with only 25 of them purchasing Copiers.

• Of the 68 customers who purchased Copiers, only 12 of them purchased Machines.

• Of the 228 customers who purchased Bookcases, 191 and 184 purchased Binders and Paper respectively.