Additional Displays of Quantitative Data
Beyond histograms: Learn how to connect data points to visualize trends over time and understand cumulative accumulation using Polygons, Ogives, and Time-Series Plots.
Frequency Polygons
Connecting the Dots
A graph that uses points connected by line segments to represent the distribution.
A frequency polygon must describe a closed geometric shape (a polygon). To do this, we must "anchor" the graph to the x-axis by adding a class with 0 frequency at both the beginning and the end of the distribution.
Interactive Frequency Polygon Tool
Enter quantitative data to generate a Frequency Polygon. Notice how the graph starts and ends at zero (anchored) and connects class midpoints.
Enter data values above or select a sample dataset to get started.
Ogives (Cumulative Graphs)
The Power of Accumulation
An Ogive (pronounced "oh-jive") is a graph that represents the Cumulative Frequency or Cumulative Relative Frequency.
- • Plots points using Upper Class Boundaries (x-axis) and Cumulative Frequency (y-axis).
- • Connect points with straight lines.
- • Starts at 0 on the y-axis at the lower boundary of the first class.
- • Never slopes downward (data only accumulates!).
Ogives are powerful for answering questions like:
"What score represents the bottom 50% of the class?"
Interactive Ogive (Cumulative Frequency) Tool
Enter data to generate an Ogive. The graph plots Upper Class Boundaries against Cumulative Frequency.
Enter data values above or select a sample dataset to get started.
Time-Series Plots
Tracking Over Time
Obtained by plotting the time on the horizontal axis and the variable's value on the vertical axis. Points are connected by line segments.
Used primarily to identify trends (long-term movements) and cycles in data over time.
Trend vs. Seasonality
A long-term upward or downward movement (e.g., Stock market over 10 years).
Regular, repeating cyclic patterns (e.g., Ice cream sales peaking every July).