Stock to flow: stock_to_flow

Syntax

stock_to_flow ( op )

Input parameters

op	the operand

Examples of valid syntaxes

stock_to_flow ( ds_1 )

Semantics for scalar operations

This operator does not perform scalar operations.

Input parameters type

op

dataset { identifier < time > _ , identifier _* , measure<number> _+ }

Result type

result

dataset { identifier < time > _ , identifier _* , measure<number> _+ }

Additional Constraints

The operand dataset has an Identifier of type time, date or time_period and may have other Identifiers.

Behaviour

The statistical data that describe the “state” of a phenomenon on a given moment (e.g. resident population on a given moment) are often referred to as “stock data”.

On the contrary, the statistical data that describe “events” which can happen continuously (e.g. changes in the resident population, such as births, deaths, immigration, emigration), are often referred to as “flow data”.

This operator takes in input a Data Set of time series which is interpreted as stock data and, for each time series, calculates the corresponding flow data by subtracting from the measure values of each regular period the corresponding measure values of the previous one.

The stock_to_flow operator can be applied only on Data Sets of time series and returns a Data Set of time series. The result Data Set has the same Identifier, Measure and Attribute Components as the operand Data Set and contains the same time series as the operand, because the time series Identifiers (all the Identifiers except the reference time Identifier) are not changed.

The Attribute propagation rule is not applied.

As mentioned in the section “Behaviour of the Time Operators”, the operator is assumed to know which is the time Identifier as well as the period of each time series.