4.6 When just Value Added is considered (i.e. stripping out inter industry purchases) the total economic impact was almost $3.9 billion in 2009. GVA is essentially the components of Gross Output that are distributed as wage income, profits, interest, taxes and in the form of depreciation. GVA is used as a standard measure of wealth generation and represents Gross Output minus the costs of all bought in goods and services. Using a conversion rate of 1US$: £0.6, then shale gas production in the Pennsylvanian Marcellus Shale generates an equivalent GVA of some £2.3 billion.