A user-defined formula within a data summarization tool allows for computations based on other items in the same field. For instance, if a pivot table summarizes sales by product category, such a feature enables the creation of a new category that represents the difference between the sales of two existing categories. This customized computation exists solely within the pivot table and does not alter the underlying dataset.
The utilization of this feature allows for enhanced data analysis and report generation. It facilitates direct comparisons and derives insights from existing data without requiring modifications to the original source. Historically, this functionality has been a significant component of data analysis software, enabling users to perform complex calculations within a familiar and intuitive interface.