Made up numbers round

From The Evening Standard:

A third runway at Heathrow will not benefit Britain as much as previously claimed, ministers admitted today. They accepted that a new way of measuring the cost of pollution, introduced just six months after the Government-backed Heathrow expansion, means the economic boost from it would now be lower...

The Department for Transport put the monetised net benefit of another runway at £5.5 billion using the then published values for the shadow price of carbon and assuming the number of flights were to rise to 702,000 a year. But last July the Department for Energy and Climate Change introduced an assessment method for the cost of carbon based on mitigating the effects of pollution rather than the damage caused...

A Lib-Dem analysis of the plans based on the changing cost of carbon found that environmental damage from another runway would cost £4.5 billion more than originally assessed — a total of £9.3 billion.

*sigh*

As any cost accountant knows, the relevant cost is the lower of:
a) the cost of the damage, and
b) the cost of preventing the damage.

For example, if you have a few slates missing from your roof, the cost is the lower of:
a) the cost of the damage from the leaks etc (many £1,000s), and
b) the cost of getting a roofer in (a couple of £100),
= a couple of £100.

Conversely, you might have a pinprick leak in your outdoor swimming pool*; the relevant cost is the lower of:
a) the cost of the damage (an extra few £1 a year for pumping in slightly more tap water than otherwise), and
b) the cost of draining the pool, digging a huge great hole and having a bit more sealant applied (tens of £1,000s),
= a few £1 a year.

Under The New Maths, the cost of the pinprick leak in your outdoor swimming pool is in fact tens of £1,000s.

Twats.

*/sigh*

* I don't have an outdoor swimming pool in my garden, and I doubt whether many of you do either, but it was the first thing that sprang to mind.