The Northern Ireland Index of Production (IOP) is one of the earliest official indicators of the performance of Northern Ireland industry and, as such, represents an important short-term measure of change in a significant area of the economy.
The IOP is a quarterly sample survey of around 1,000 companies designed to provide a general measure of changes in the output of the Manufacturing, Electricity, Gas, Water and Mining & Quarrying industries. It is based on up-to-date information about the output and sales of the production industry. The Index is published in March, June, September and December of each year.
