Pictographs - Using Symbols to Show Data
A pictograph (also called a pictogram) uses pictures or symbols to represent data. Each symbol stands for a fixed number of items. Pictographs make data visual and easy to compare at a glance.
Key Features of a Pictograph
- Title – tells the reader what the pictograph shows.
- Key – states what one symbol represents (e.g. each star = 5 books).
- Rows or columns – each category has its own row or column of symbols.
- Half symbols – used when a value falls between whole-symbol amounts.
Worked Examples
The pictograph below shows books read by four students in one month. Key: 1 book symbol = 4 books.
| Student | Symbols | Books read |
|---|---|---|
| Ali | ★★★ | 3 × 4 = 12 |
| Beth | ★★★★★ | 5 × 4 = 20 |
| Cam | ★★ | 2 × 4 = 8 |
| Dana | ★★★★ | 4 × 4 = 16 |
Total books = 12 + 20 + 8 + 16 = 56 books.
Key: 1 symbol = 10 items. A row shows 3.5 symbols. How many items does this represent?
3.5 × 10 = 35 items. The half symbol represents 5 items.
Drawing a Pictograph
- Write a clear title.
- List all categories in a column on the left.
- Choose a key value that makes the numbers easy to represent (avoid fractions where possible).
- Draw the correct number of symbols in each row.
- Always include the key.
Advantages and Limitations
| Advantages | Limitations |
|---|---|
| Easy to read quickly | Hard to show exact values that do not fit the key |
| Visually appealing | Half or quarter symbols are approximate |
| Good for simple comparisons | Not suitable for large or complex datasets |
Key Takeaways
- Each symbol in a pictograph represents a fixed number of items – always check the key.
- Multiply the number of symbols by the key value to find the frequency.
- Half symbols represent half the key value.
- Pictographs are best for simple, small datasets with categories that differ noticeably.
Practice Questions
- Key: 1 circle = 6 cars. A row shows 4.5 circles. How many cars?
- Draw a pictograph for: Apples 24, Oranges 36, Bananas 18, Grapes 12. Use a key of 1 symbol = 6 fruits.
- A pictograph shows rainfall. Key: 1 cloud = 20 mm. January: 3 clouds, February: 2.5 clouds, March: 4 clouds. Which month had most rain? How much more than February?
- Why might you choose a bar chart over a pictograph for a large dataset?
- In a pictograph where the key is 1 symbol = 50 items, how many symbols would represent 175 items?