Which of the following methods is NOT used to calculate Gross Domestic Product (GDP)?

To understand which methods are not used to calculate Gross Domestic Product (GDP), we first need to know the main methods that are actually used. GDP can be calculated using three main approaches: the production approach, which looks at the total value of all goods and services produced; the income approach, which adds up all incomes earned by individuals and businesses; and the expenditure approach, which considers all spending on goods and services. If a method does not fit into these categories, it is likely not used to calculate GDP. For example, using population size alone to determine economic performance would not be a valid method for calculating GDP. Thus, any method that does not involve production, income, or spending is not relevant for GDP calculation.