Aggregaatioon

Aggregaatioon is the process of combining multiple individual items into a single summary or higher-level unit. In statistics, data analysis, and information systems, aggregation reduces detail to enable interpretation, comparison, and reporting. The term is used in Estonian-language texts as aggregaatioon, closely related to aggregatsioon.

Aggregation can apply to numbers, measurements, observations, or categorical data. It is used to create summaries such as totals, averages, or counts, and to convert granular data into broader categories or time periods, for example turning daily sales into monthly totals.

Common methods include sum, count, mean, median, minimum and maximum, and weighted variants. For distributions, percentiles or quantiles may be used. In time-series data, moving averages or rolling sums are forms of temporal aggregation.

In databases and data processing, aggregation is performed by aggregate functions (for example, SUM, AVG, COUNT, MIN, MAX) and grouping operations. In large-scale analytics, frameworks such as MapReduce and OLAP environments support roll-up and drill-down to different aggregation levels.

Aggregation can obscure variability and individual differences, especially when the granularity is coarse. Care is required to document the chosen level of aggregation, units, and any assumptions, to preserve interpretability and avoid misleading conclusions. See also: aggregation, data aggregation.