Pictographs

A pictograph uses small pictures to display data. One picture stands for a fixed number of items, and the rows of pictures let you compare categories with a single glance. They are friendly, easy to read, and great for small data sets.

Concept

To draw a pictograph you need three things:

1. A list of categories (the things you are comparing).
2. A frequency for each category.
3. A choice of scale , that is, the number of items each picture stands for.

For example, suppose a school surveyed $50$ students about their favourite fruit:

If we let one mango picture stand for $5$ students, the pictograph becomes:

(In a real pictograph each "M" would be a small drawing of a mango or fruit.)

Notice three things:

• The scale ($1$ picture $= 5$ students) is always stated next to or below the pictograph. Without a scale, the picture is meaningless.
• All categories use the same picture and the same scale. You can't have apples standing for $5$ and oranges for $10$.
• If a category's count is not a clean multiple of the scale, you draw a partial picture , half a fruit for half the scale.

Pictographs are great when:

• The numbers are small.
• Audiences include young children or non-specialists.
• The categories are few (say $5$ or fewer).

They become awkward when numbers are huge (you don't want to draw $200$ pictures) or when precision matters (a half-picture can be ambiguous).

Worked examples

Example 1. Read this pictograph. Scale: $1$ ⭐ = $10$ books.

How many books did each class collect for the book drive?

• Class 6: $5 \times 10 = 50$ books.
• Class 7: $3 \times 10 = 30$ books.
• Class 8: $4 \times 10 = 40$ books.

Example 2. Six students sold tickets: Asha $24$, Babu $16$, Chitra $40$, Dipan $32$, Eva $8$, Farah $48$. Draw a pictograph with scale $1$ picture = $8$ tickets.

Example 3. A pictograph shows daily rainfall: scale $1$ ☁️ = $5$ mm.

What is the total rainfall for the week?

• Mon: $10$ mm. Tue: $20$ mm. Wed: $5$ mm. Thu: $0$ mm. Fri: $15$ mm.
• Total: $50$ mm.

Example 4. A village has $120$ children attending each of $6$ schools. Why is "$1$ picture = $1$ child" a bad scale choice here?

• Because you would have to draw $120$ pictures per row , $720$ pictures total. Unreadable.
• A scale of $1$ picture = $20$ children would give $6$ pictures per row , clean and clear.

Try it yourself

1. With scale $1$ 🍦 = $4$ ice-creams, draw a pictograph for sales: Mon $20$, Tue $16$, Wed $24$, Thu $12$, Fri $32$.
2. In a pictograph for "books read in a year", scale $1$ 📕 = $5$ books, a child has $3.5$ 📕. How many books?
3. A pictograph shows car sales by colour: red $14$ cars, blue $7$, white $21$, with scale $1$ 🚗 = $7$ cars. Make the table.
4. Why must the scale always be written next to the pictograph?
5. Suggest a good scale for a pictograph showing class strengths of $30, 25, 40, 35, 20$.
6. Can you use different pictures for different categories in the same pictograph? Why or why not?
7. Design: draw a pictograph showing how many cousins each of your $4$ friends has.

Activity

Cricket scoreboard. Pick the last $5$ matches of any cricket team (you can use family memory or a sports page). Note each match's total runs scored by India (or any team). Choose a sensible scale , say $1$ 🏏 = $20$ runs , and draw a pictograph. Discuss with a friend: would a scale of $1$ 🏏 = $5$ runs have been better? Worse? Why?