Data Visualisation - lesson 5 | HackIndia Skills

Key point

One job

A chart label should remove guessing. Your viewer should know what is measured, the unit, the time period, and the main takeaway without asking you on a call.

For a hackathon demo, assume a recruiter or judge sees your dashboard for 20 seconds. Labels must carry the story.

What to label

Every useful chart needs a clear title, axis labels, units, and a time range if time is involved. If the chart uses categories, make the category names readable.

If one number matters most, label it directly. Do not make the viewer match colours to a legend when there are only one or two important lines.

Your to-do

Label checklist

Do each one yourself, then tap it to tick it off. The ticks are only a checklist for you: they are not marked or scored.

Write a title as a question or answer, not as a file name.
Name each axis with the metric and unit, such as Cost in ₹ or Time in minutes.
Show the time window, such as Jan 2026 or last 7 days.
Label the key point directly, such as Peak wait: 14 min.
Add a short note if the data is filtered, estimated, or user-entered.

0 of 5 done

Common mistake

Weak labels

Beginners often write titles like Graph 1, Users, or Analysis. These labels do not tell anyone what decision the chart supports.

Another common mistake is using abbreviations only your team knows. DAU, GMV, NPS, and SLA may be fine for your team, but expand them once if your project is shown to outsiders.

Example

Before and after

This is the same chart idea with better labels. The second version tells a clearer story in a project dashboard for a campus canteen queue app.

Weak:
Title: Queue
X-axis: Time
Y-axis: Count
Legend: Series 1

Better:
Title: When is the canteen queue longest?
X-axis: Time of day, 9 AM to 5 PM
Y-axis: Students waiting
Direct label: Peak queue: 38 students at 1:15 PM
Note: Data from 42 user check-ins on 12 Feb

Tip

Use AI carefully

You can ask ChatGPT, Gemini, or Claude to improve chart labels. Paste your chart question, metric, unit, time period, and audience.

Check the output yourself. AI often makes the title sound too broad, adds claims not in your data, or forgets the unit.

Prompt:
I am making a dashboard chart for a hackathon project.
Question: Are users completing onboarding faster after our change?
Metric: Median onboarding time
Unit: minutes
Time period: 7 days before and 7 days after change
Audience: recruiters and hackathon judges
Suggest a clear chart title, axis labels, and one short note.

Check:
- Does it include minutes?
- Does it mention the before/after period?
- Does it avoid claiming causation if the data only shows a change?

Notes are labels too

A note is not an apology. It is context. Use it when the viewer could misunderstand where the data came from or what is excluded.

Good notes are short: Sample: 31 hostel students. Excludes failed payments. Amounts are in ₹. These make your dashboard look more honest.