Which summary measures are best suited for nominal data?

Which summary measures are best suited for nominal data?

• A. Mean and standard deviation
• B. Median and interquartile range
• C. Correlation coefficient
• D. Frequencies and percentages

Answer: (D)

Nominal data are categories with no inherent order, so arithmetic summaries like a mean or standard deviation aren’t meaningful. The best way to describe them is to show how many observations fall into each category and what proportion that represents, i.e., frequencies and percentages. This provides a clear view of the distribution across categories and highlights the most common category. Other summaries rely on numerical ordering or relationships between variables and aren’t appropriate for nominal data.

Nominal data are categories with no inherent order, so arithmetic summaries like a mean or standard deviation aren’t meaningful. The best way to describe them is to show how many observations fall into each category and what proportion that represents, i.e., frequencies and percentages. This provides a clear view of the distribution across categories and highlights the most common category. Other summaries rely on numerical ordering or relationships between variables and aren’t appropriate for nominal data.