The underground economy refers to used product sellers who sell in secondary markets. It is thought to make up 3-30% of the US gross national product.
Explanation:
Household production refers to goods and services people produce for themselves.
Underground economy refers to buying and selling of goods and services that are concealed from the government to avoid taxes or regulations or because the goods and services are illegal.
If you know how much the economy works for a brief time, it doesn't matter.
If one knows how goods and services are produced for a decade or further, it might be more important to omit domestic production and development in the underground economy.