Individual businesses are classified according to the products they make or the services they provide. If they produce more than one product they are classified according to their main or principal product. This means that most domestic production lies on the diagonal line on the supply table (i.e. the Construction industry mainly produces construction products). However, there are some off-diagonal elements in the table. These represent secondary production and by-products other than the principal product of the industry. The Supply table is relatively sparse because most producers make a limited range of products. Some values are not published due to the data being disclosive. The main body of the Supply table shows domestic supply at basic prices – i.e. the value received by the producers.
The columns on the right of the main body (section 2) show the change from the domestic supply at basic prices to the supply at purchaser’s prices through the addition of imports of products, distributors’ trade margins on products and taxes on products (e.g. VAT) less subsidies on products. Summing across these columns and those in the main body of the table gives the total supply of products at purchasers’ prices i.e. the value paid by purchasers excluding any refundable VAT.
Interpretation of the 2017 Supply Table
The Supply table is presented by 62 product group. For the substantial majority of industries, production of the industry’s principal product and services accounted for over 80 per cent of their total output. Reading across the rows in the table we can see that the total domestic value of textiles produced by Northern Ireland businesses was £463 million (see column headed domestic supply). In addition textiles to the value of £233 million were imported in 2017. The total supply of this product equates to £1,150 million.