Statistical Charts and Diagrams (Copy)
Cheat Sheet: Drawing and Interpreting Statistical Diagrams (IGCSE Mathematics 0580 – CORE)
Topic: Bar Charts, Pie Charts, Pictograms, Stem-and-Leaf Diagrams, Frequency Distributions
1. Bar Charts
- Bars are equal width and height represents frequency.
- Gaps between bars for discrete data.
- Composite (stacked) bar charts: Bars stacked on top of each other to show parts of a total.
- Dual (side-by-side) bar charts: Two bars drawn side-by-side for each category to compare two sets of data.
Key Points:
- Label x-axis (categories) and y-axis (frequencies).
- Use even spacing and scale.
2. Pie Charts
- Circle divided into sectors.
- Each sector represents a category.
- Angle for each sector:
Angle=(FrequencyTotal Frequency)×360°text{Angle} = left( frac{text{Frequency}}{text{Total Frequency}} right) times 360°
Key Points:
- Total circle = 360°.
- Use a protractor to measure angles.
- Label sectors clearly.
3. Pictograms
- Use pictures or symbols to represent quantities.
- Each symbol represents a fixed number (e.g., 1 symbol = 5 people).
- Half symbols can be used when needed.
Key Points:
- Always include a key showing what each symbol represents.
4. Stem-and-Leaf Diagrams
- Data split into stems (leading digits) and leaves (last digits).
- Data should be in order.
- Key must be included (e.g., “2 | 5 means 25”).
Example:
| Stem | Leaf |
|---|---|
| 2 | 3 5 7 |
| 3 | 1 6 8 |
Key: 2 | 3 means 23.
5. Simple Frequency Distributions
- Table showing each data value or category and its frequency.
- Can be for small sets of discrete data.
Example:
| Value | Frequency |
|---|---|
| 1 | 2 |
| 2 | 5 |
| 3 | 3 |
Key Points:
- Clear headings for “Value” and “Frequency”.
- Useful for summarizing raw data.
6. Important Tips
- For bar charts: even spaces and uniform width.
- For pie charts: careful, accurate angles.
- For pictograms: symbols must be consistent and clear.
- For stem-and-leaf: order leaves and always add a key.
- For frequency tables: ensure frequencies add correctly.
This cheat sheet fully covers CORE-level drawing and interpretation of bar charts, pie charts, pictograms, stem-and-leaf diagrams, and simple frequency distributions.