BBC Scotland today reports on developments at Grangemouth. I have no quibble with the content of their piece. However it states "Grangemouth is already said to be responsible for about 10% of Scotland's gross domestic product (GDP)" - note the weasel-words "is said to be"; translation: "I overheard someone say this, it may or may not be true, but sounds impressive and I can't be bothered investigating". This is unacceptable journalism.
Let me help the BBC out: I have no idea about the profit and loss accounts that could be attributed to the Grangemouth plant; but I can at least do back of the envelope calculations.
# Scotland's GDP is approximately £150bn so 10% is around £15bn
# Country GDP, as a concept, is analogous to Company operating profit (before depreciation). Wikipedia makes this clear in 2nd paragraph on GDP.
# Grangemouth has 800 employees and so its wage bill is highly likely to be substantially less than £100m. Simply the payments to capital would then have to be approaching £15bn for this plant to be "responsible" for 10% of Scotland's GDP.
So whilst Grangemouth may be "said to be responsible" for 10% of Scotland's GDP, this is only "said" by people who don't know what they are talking about. Business and economics journalists do not (or should not) have this excuse.
Now perhaps the value of Grangemouth's sales approaches £15bn (this may or may not be true). So what? It will have paid £14bn-odds for the raw materials and its value added (operating profit before depreciation) will be much lower. Even if it is true that Grangemouth's revenues are 10% of Scotland's GDP, comparing these figures is meaningless. This is like saying there are roughly the same number of nano-meters in 10cm as there are miles in the Earth-Sun distance: it's a true statement, but comparing these numbers without noting that they measure different things adds no information.