What type of graph is commonly used to illustrate correlations?

• A. Bar chart.
• B. Line graph.
• C. Pie chart.
• D. Scatter diagram.

Answer: (D)

A scatter diagram is commonly used to illustrate correlations because it displays individual data points on a two-dimensional graph, where each axis represents a different variable. This allows for a clear visual representation of the relationship between the two variables being studied. When points are clustered together in a specific direction (either positive or negative), it indicates the presence of a correlation. The closer the points are to forming a straight line, the stronger the correlation.

In contrast, bar charts are more suited to comparing categorical data, line graphs typically represent data points over a period of time rather than correlations between two variables, and pie charts are used for showing proportions of a whole rather than relationships between different sets of data. Therefore, the scatter diagram provides the most appropriate format for analyzing and presenting correlations.