Household electricity approach

The Household Electricity Approach to measuring the size of the underground economy or black market of a country exploits the presumed relationship between household electrical consumption and a country's GDP. It assumes that undeclared economic activity still needs to use resources, such as electricity, to function. Since electricity consumption is generally well known it can be used as an indicator of economic activity that is not otherwise declared.

Source: Wikipedia — Household electricity approach (CC BY-SA 4.0)