BUSI2001 Chap.3 Tableau Essentials for Data Visualisation
Tableau Essentials for Data Visualisation
Visualisation makes patterns in data visible quickly enough to inform decisions, and Tableau is the course's tool for building it. This chapter explains how to choose a chart from the question being asked, how dimensions slice a view while measures are aggregated, and why the default sum is often the wrong aggregation.
It shows how relating a returns table to an orders table on a shared identifier lets a return rate reveal a region that raw counts hide, and how geographic roles and date types unlock maps and time hierarchies. The chapter closes with practice on the crowdsourced ping pong activity and on repairing a dataset whose fields Tableau has misread.
Each technique is practised on business questions, so the habit you build is choosing a view that a manager could act on.
What this chapter covers
- 01
Purpose of data visualisation
- 02
Choosing a chart type
- 03
Dimensions and measures
- 04
Aggregation choices
- 05
Joining orders and returns
- 06
Geographic roles
- 07
Date hierarchies
- 08
Storytelling with titles
Worked example · free
Choosing the right chart for four business questions
- +1(a) compares categories: a sorted bar chart with Category on Rows and SUM(Sales) on Columns.
- +1(b) shows change over time: a line chart using the continuous month of Order Date.
- +1(c) tests a relationship: a scatter plot of Discount against Profit at order level.
- +1(d) asks where: a filled map, after State carries a geographic role.
Key terms
- Dimension
- A categorical field in Tableau that divides a view into groups, such as Region or Category.
- Measure
- A numeric field in Tableau that is aggregated within each group, such as Sales or Profit.
- Geographic role
- A Tableau setting that tells the software a field holds places, so it can plot them on a map.
- Data source page
- The Tableau screen where files are connected, related and given their data types before analysis.
Tableau Essentials for Data Visualisation FAQ
Why does Tableau show sums by default?
Tableau aggregates measures, and SUM is the default because totals suit many sales questions. For ages, scores or ratings a sum is meaningless, so change the aggregation to average or count. When groups differ in size, compute a rate with a calculated field rather than comparing totals that simply reflect group size.
Why must returns be joined to orders before analysis?
Returns sit in a separate table, so on their own they cannot show what share of each region's orders came back. Relating the tables on a shared Order ID lets Tableau count returned orders within each region and divide by all orders there. Check afterwards that the join has not duplicated any rows.
How do I get a free Tableau licence?
The course points students to Tableau's academic program for students, where a free licence can be requested by following the prompts on the site. After installing, Tableau's own training videos and learning materials are available, and the course data files can be used straight away for practice.
When is a pie chart a poor choice?
Pie charts struggle when there are many categories or when slices are similar in size, because people compare angles less accurately than lengths. A sorted bar chart usually shows the same comparison more clearly. Reserve a pie for two or three parts of a whole where the message is simply which part dominates.
Assessment move
Install Tableau through the academic program early so software problems do not collide with the first assignment. Then practise with one dataset that has both a date field and a location field, as the workshop task requires. Build four views from it, one for each chart family in the chapter figure, and give every view a title that states its finding in a sentence.
For each view, write down which fields are dimensions and which are measures, and check the aggregation on every measure. Practise one join between two tables on a shared identifier and confirm the row count afterwards. When you present a chart to classmates in the workshop, ask them to state the main finding without your help, and note in your weekly reflection what they understood differently.
That feedback loop is the fastest way to improve visual storytelling, and it doubles as portfolio material. Collect three charts from news or business reports that you find confusing, and redesign each in Tableau with a clearer chart type and a finding-led title. Explaining why your version is clearer is good practice for justifying visual choices in the Business Data Analysis.
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