Overview
This lecture explains how to create a histogram from a frequency or relative frequency distribution using spreadsheet software.
Creating a Histogram from Frequency Distribution
- Select frequency values in your spreadsheet.
- Go to Insert and choose the Clustered Column chart to visualize the frequencies.
- The initial horizontal axis may not be labeled with class intervals.
- To remove gaps between bars, right-click a bar, select Format Data Series, and adjust gap width to zero.
- To label the horizontal axis with class intervals, right-click the chart, select Select Data, then Edit Horizontal Axis Labels and choose the class interval cells.
- Always label the vertical axis as “Frequency” for a frequency histogram.
- The horizontal axis should be labeled according to the class intervals relevant to the data set.
Creating a Relative Frequency Histogram
- Use relative frequency values instead of raw frequencies.
- Follow the same steps for creating and formatting the histogram as above.
- Use the same class intervals as with the frequency histogram.
Interpreting Frequency and Relative Frequency Histograms
- Both histograms have the same shape because relative frequencies are proportional to raw frequencies.
- The only difference between them is the scaling on the vertical axis.
- Both histograms convey the same information about the data distribution.
Key Terms & Definitions
- Histogram — a bar graph representing the frequency or relative frequency of data within class intervals.
- Frequency Distribution — a table showing the number of data points in each class interval.
- Relative Frequency — the proportion or percentage of data points in each class interval.
- Class Interval — a range of values grouped together on the horizontal axis.
Action Items / Next Steps
- Practice creating both frequency and relative frequency histograms using sample data in a spreadsheet.
- Label all chart axes and class intervals clearly in future assignments.