Bar Graph Overview and Basics

Overview

This lecture introduces bar graphs, explains their features, and demonstrates how to construct one with categorical data.

Bar graphs use rectangles (bars) to visually display categorical data.
Each bar represents a different category, with the height or length showing frequency.
Bars should never touch, as touching bars indicate a histogram, not a bar graph.
Bar graphs can be oriented vertically or horizontally without changing their meaning.

Example data: Number of people with each eye color (Brown, Blue, Green/Hazel).
X-axis represents categories (eye color), and Y-axis represents frequencies.
Use labeled tick marks on the Y-axis for clarity (e.g., 5, 10, 15, 20, 25).
Always label both axes (e.g., "Eye Color" and "Frequencies").
Draw each bar up to the correct frequency value for each category.
Bars should be spaced evenly and not touch each other.
Optional: Use different colors for each bar or label each bar with its value for clarity.

Bar Graph — a chart that displays categorical data using separated bars to show frequency.
Histogram — a similar chart where bars touch, used for quantitative data with continuous intervals.
Category — a distinct group or label within the data (e.g., eye color).
Frequency — the count of occurrences within each category.