A pivot table is used to cross-tabulate frequencies of occurrence of two variables, also known as creating a contingency table or two-way frequency table.
We would use a pivot table to cross-tabulate frequencies of occurrence of two variables. This is option a) in the provided list of possible uses for a pivot table. Pivot tables are a powerful feature in many spreadsheet applications that allow users to organize and summarize complex data. They facilitate the analysis of bivariate data by making it easier to create two-way frequency tables, also known as contingency tables, which display the marginal frequencies or distributions observed in the dataset.
Using pivot tables, one can easily calculate relative frequencies, and define marginal and conditional distributions from the data, aiding in the determination of empirical probabilities. Unlike scatter plots, which display data points, and line graphs, which connect frequency points with line segments, pivot tables do not visualize data in a graphical format such as 3D scatter plots but rather in a tabular format. As such, the correct answer is a), to cross-tabulate frequencies of occurrence of two variables.