Aggregation

Aggregation
Description	Aggregation of categorical data involves the gathering of information for statistical analysis and expressing it in a summarized form.
Why to use	Numerical Analysis – Data Preparation
When to use	When you want to collect specific information about particular groups based on specific variables.	When not to use	On textual data.
Prerequisites	It should be used on numerical and categorical data.
Input	Any dataset that contains categorical as well as numerical data.	Output	Aggregated numerical or categorical data.
Statistical Methods used	Sum Mean Mode Minimum Maximum Count Count (Distinct) Standard Deviation Variance	Limitations	Sometimes using only aggregation is not enough as it gives only single level analysis. You may need to use other methods to get accurate results.

Aggregation is a group-by algorithm in which a given data is grouped for a certain categorical data variable like name, date, color, educational level and so on. The data that is grouped is the numerical data and is called the Aggregate Function. You can use this algorithm without selecting the GroupBy function.