Which graph is appropriate for scores measured on a nominal scale?

Which graph is appropriate for scores measured on a nominal scale?

• A. Only a histogram
• B. Only a polygon
• C. Either a histogram or polygon
• D. Only a bar graph

Answer: (D)

Nominal data are categories with no natural order, so the distribution is best shown with a bar graph. In a bar graph, each category sits on the horizontal axis and the height of its bar reflects frequency or percentage, making it easy to compare how many observations fall into each category. Bars are separated to emphasize that the categories are distinct and not connected by equal intervals. Histograms are designed for continuous data and group scores into numeric bins with equal spacing, which isn’t meaningful for nominal categories. Polygons connect data points to show a continuous trend, which also isn’t appropriate when the x-axis represents separate, unordered categories. For this reason, a bar graph is the appropriate choice for nominal-scale scores.

Nominal data are categories with no natural order, so the distribution is best shown with a bar graph. In a bar graph, each category sits on the horizontal axis and the height of its bar reflects frequency or percentage, making it easy to compare how many observations fall into each category. Bars are separated to emphasize that the categories are distinct and not connected by equal intervals.

Histograms are designed for continuous data and group scores into numeric bins with equal spacing, which isn’t meaningful for nominal categories. Polygons connect data points to show a continuous trend, which also isn’t appropriate when the x-axis represents separate, unordered categories. For this reason, a bar graph is the appropriate choice for nominal-scale scores.