Purpose: Compare categories of data.
Data Type: Categorical or discrete numerical
Description: Bars are used to show the size or frequency of each category.
Example:
Number of students in different majors
Sales per product category
Example: Favorite Fruit Survey
| Fruit | Number of People |
|---|---|
| Apple | 12 |
| Banana | 9 |
| Orange | 7 |
| Mango | 5 |
Use a bar graph to compare the popularity of each fruit.
Purpose: Show trends over time.
Data Type: Continuous numerical data (especially over time)
Description: Points are connected by lines to show changes over intervals.
Example:
Temperature changes throughout the week
Stock prices over months
Example: Monthly Sales (£ in thousands)
| Month | Sales |
|---|---|
| Jan | 22 |
| Feb | 25 |
| Mar | 30 |
| Apr | 28 |
| May | 35 |
Use a line graph to show the trend of sales over time.
Purpose: Show the distribution of a numerical dataset.
Data Type: Continuous numerical
Description: Like a bar graph, but bars touch. Used to group values into intervals (bins).
Example:
Heights of people in a group
Exam scores distribution
Example: Test Scores of 20 Students
| Score Range | Frequency |
|---|---|
| 40–49 | 2 |
| 50–59 | 5 |
| 60–69 | 8 |
| 70–79 | 3 |
| 80–89 | 2 |
Use a histogram to show how scores are distributed.
Purpose: Show parts of a whole as percentages.
Data Type: Categorical
Description: A circle divided into slices representing proportions.
Example:
Market share of companies
Budget spending breakdown
Example: Time Spent on Daily Activities
| Activity | Hours |
|---|---|
| Sleep | 8 |
| Work | 9 |
| Exercise | 2 |
| Leisure | 3 |
| Others | 2 |
Use a pie chart to show what percentage of the day is spent on each activity.
Purpose: Show spread, median, and outliers in a dataset.
Data Type: Numerical
Description: Shows minimum, Q1, median, Q3, and maximum.
Example:
Comparing test scores across different classes
Income distributions
Example: Heights (cm) of Two Groups
| Group A | Group B |
|---|---|
| 160 | 170 |
| 165 | 172 |
| 162 | 169 |
| 158 | 174 |
| 164 | 175 |
Use a box plot to compare the spread and central tendency of both groups.
Purpose: Show frequency of small numerical datasets.
Data Type: Discrete numerical
Description: Dots represent data points above a number line.
Example:
Number of pets owned by students
Daily absences over a week
Example: Number of Pets Owned by Students
| Number of Pets | Frequency |
|---|---|
| 0 | 3 |
| 1 | 5 |
| 2 | 6 |
| 3 | 4 |
| 4 | 2 |
Use a dot plot to show how many students own how many pets.
7. Scatter Plot
Purpose: Show the relationship (correlation) between two variables.
Data Type: Two numerical variables
Description: Each point shows one observation for two variables (x, y).
Example:
Height vs. weight
Hours studied vs. test score
Example: Hours Studied vs. Test Score
| Hours Studied | Test Score |
|---|---|
| 1 | 52 |
| 2 | 55 |
| 3 | 60 |
| 4 | 68 |
| 5 | 75 |
| 6 | 80 |
Use a scatter plot to explore the relationship between studying and scores.
| Graph Type | Data Type | Best For | Example |
|---|---|---|---|
| Bar Graph | Categorical | Comparing categories | Favorite fruit of students |
| Line Graph | Numerical (over time) | Showing trends | Monthly sales over a year |
| Histogram | Continuous numerical | Distribution of data | Ages of participants |
| Pie Chart | Categorical | Proportions | Department budget allocations |
| Box Plot | Numerical | Spread and outliers | Salaries in different cities |
| Dot Plot | Discrete numerical | Small data distributions | Number of siblings per student |
| Scatter Plot | Two numerical values | Correlation between variables | Height vs. weight |
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