Quality is a subjective notion and encompasses all aspects of how well a product meets users’ needs. It is inherently a multi-faceted concept that cannot be easily defined; any chosen definition is likely to change over time as new aspects gain importance following the evolving users’ needs....

The quality of the geographical breakdown in the balance of payments and related statistics (such as international trade in goods, trade in services and foreign direct investment (FDI) statistics) can be assessed by means of comparisons with mirror data in order to assess bilateral asymmetries....