Which types of graphs are used for data from an interval scale?

Which types of graphs are used for data from an interval scale?

• A. Histograms and bar graphs
• B. Polygons and bar graphs
• C. Histograms and polygons
• D. Histograms, bar graphs, polygons

Answer: (C)

For interval-scale data, distributions are best shown with histograms and frequency polygons. The key idea is that interval data are continuous with equal intervals between values, so you want graphs that reflect that continuity across a numeric axis. A histogram bins the data into consecutive intervals and uses touching bars to show how often values fall in each range, which reveals the shape, skew, and spread of the distribution. A frequency polygon does something similar by plotting the frequencies at the bin midpoints and connecting them with a line, giving a clear view of the distribution’s overall form without the feel of discrete bars. Bar graphs, by contrast, are designed for categorical data with separate, distinct categories, so they don’t convey the continuous nature of interval data as effectively. Thus, histograms and polygons are the appropriate graph types for interval-scale data.

For interval-scale data, distributions are best shown with histograms and frequency polygons. The key idea is that interval data are continuous with equal intervals between values, so you want graphs that reflect that continuity across a numeric axis. A histogram bins the data into consecutive intervals and uses touching bars to show how often values fall in each range, which reveals the shape, skew, and spread of the distribution. A frequency polygon does something similar by plotting the frequencies at the bin midpoints and connecting them with a line, giving a clear view of the distribution’s overall form without the feel of discrete bars. Bar graphs, by contrast, are designed for categorical data with separate, distinct categories, so they don’t convey the continuous nature of interval data as effectively. Thus, histograms and polygons are the appropriate graph types for interval-scale data.