Data Foundations · Module 7

Visualisation basics (so charts do not lie to you)

Visualisation is part of data literacy.

22 min 4 outcomes Data Foundations

Previously

Open data, data sharing, and FAIR thinking

Open data is not “everything on the internet”.

This module

Visualisation basics (so charts do not lie to you)

Visualisation is part of data literacy.

Data quality and meaning

Quality means data is accurate (close to the truth), complete (not missing key pieces), and timely (fresh enough to be useful).

Progress

Mark this module complete when you can explain it without rereading every paragraph.

Why this matters

Two charts show the same numbers.

What you will be able to do

1 Explain visualisation basics (so charts do not lie to you) in your own words and apply it to a realistic scenario.
2 Visualisation is how you argue with evidence. Poor charts mislead quietly.
3 Check the assumption "Axes are honest" and explain what changes if it is false.
4 Check the assumption "Context is included" and explain what changes if it is false.

Before you begin

No previous technical background required
Read the section explanation before using tools

Common ways people get this wrong

Misleading scale. Small visual choices can create a false story. Be careful with scales and baselines.
Chart without question. A chart should answer a question. Otherwise it becomes noise.

Visualisation is part of data literacy. A chart is an argument. It can be honest or misleading. The goal in Foundations is not to become a designer. The goal is to stop being fooled by bad charts, including your own.

Worked example. Same data, different story

Two charts show the same numbers. One uses a consistent scale. The other uses a cropped axis so small changes look huge. If you react emotionally to the second chart, that is not a personal flaw. That is a design choice manipulating attention.

Verification. Four questions before you trust a chart

Chart trust checklist

Run these checks before you quote a chart in a meeting.

Confirm the unit

Know whether values are counts, rates, percentages, or physical units.
Confirm the time window

Check start and end boundaries before comparing periods.
Confirm inclusion and exclusion rules

Know which users, events, or regions are inside and outside the chart.
Confirm scale integrity

Check whether axis choices exaggerate or hide changes.

Mental model

Charts are arguments

Visualisation is how you argue with evidence. Poor charts mislead quietly.

1

Data
2

Chart
3

Interpretation
4

Decision

Assumptions to keep in mind

Axes are honest. Axes and scales should not manipulate perception. Honesty builds trust.
Context is included. Without context, charts invite overconfidence and misuse.

Failure modes to notice

Misleading scale. Small visual choices can create a false story. Be careful with scales and baselines.
Chart without question. A chart should answer a question. Otherwise it becomes noise.

Check yourself

Quick check. Visualisation basics

0 of 4 opened

Why is a chart an argument

It presents an interpretation. Choices like scale and inclusion change the story.

Name two questions you ask before trusting a chart

Unit and time window, plus what is included and excluded.

What is one way a chart can mislead without lying

Cropping the axis so small changes look dramatic.

What is one reason you should not trust a chart that lacks context

Without units, definitions, and scope you cannot interpret what the numbers mean.

Artefact and reflection

Artefact

A short module note with one key definition and one practical example

Reflection

Where in your work would explain visualisation basics (so charts do not lie to you) in your own words and apply it to a realistic scenario. change a decision, and what evidence would make you trust that change?

Optional practice

Complete one guided exercise and explain your decision in plain language