A set of related data that sums up to an arbitrary total. Examples:

Market share data, either for a specific point in time, or, over time (where each variable represents the share for a brand, and each case represents a different time point).
Data from a constant-sum question in a survey, which is a type of question that presents respondents with a list of objects to be evaluated and requires that they allocate points, tokens or some other measure, to the objects according to some specified criteria (e.g., preference, usage). For example: "Thinking about your next 10 trips to the supermarket, how many will be to each of the stores shown below?".

Also known as

Compositional data

Constant-Sum Data