Data Representation

We are surrounded by data every day -- election results, temperature records, exam scores, cricket statistics. But raw numbers are hard to understand. Data representation turns those numbers into pictures and tables that tell a clear story.

Frequency Tables

A frequency table organizes data by counting how often each value or range appears.

Example: Math scores of 20 students grouped into intervals:

| Score Range | Frequency | |-------------|-----------| | 40-49 | 4 | | 50-59 | 4 | | 60-69 | 4 | | 70-79 | 3 | | 80-89 | 3 | | 90-99 | 2 |

Bar Graphs

Bar graphs use rectangular bars to compare quantities across categories. The bars have equal width with gaps between them.

Best for: Comparing discrete categories (e.g., favorite sports, population of different cities in Nepal).

Histograms

Histograms look similar to bar graphs but have no gaps between bars. They show continuous data grouped into intervals.

Key Difference: Bar graphs have gaps (discrete data). Histograms have no gaps (continuous data).

Pie Charts

Pie charts show data as slices of a circle. Each slice represents a proportion of the whole.

How to calculate the angle: Angle = (frequency / total) x 360 degrees

Example: In a survey of 60 students about favorite subjects:

• Math: 15 students = (15/60) x 360 = 90 degrees
• Science: 20 students = (20/60) x 360 = 120 degrees
• English: 10 students = (10/60) x 360 = 60 degrees
• Social Studies: 15 students = (15/60) x 360 = 90 degrees

Total angles should always equal 360 degrees.

Choosing the Right Graph

• Comparing categories: Bar graph
• Showing distribution of continuous data: Histogram
• Showing parts of a whole: Pie chart
• Showing trends over time: Line graph

Nepal Connection: Nepal's Central Bureau of Statistics uses various data representation methods to share census results. Population distribution across the seven provinces is often shown using bar graphs and pie charts.

Key Takeaways

• Frequency tables organize raw data into manageable groups
• Bar graphs compare categories; histograms show distributions
• Pie chart angles = (value/total) x 360 degrees
• Choose the right type of graph based on what you want to show