Consumer Price Index. Yes I was amazed a couple of years ago when Cyclone Larry flattened the Oz banana crop (and banana prices went up by several hundred percent overnight) when the assumption that went into the CPI calculation was that we were all eating the *same* quantity of (unavailable!) bananas, and choosing to pay several times as much, rather than just select a substitute variety of fruit. So the *calculated* impact of the banana price rise was actually much greater than the actual impact, and this drove the quarterly inflation figure up substantially. http://www.abc.net.au/lateline/content/2006/s1697960.htm)

Why would they do such a daft calculation? Bananas could (and should) have been dropped from the calculation altogether, but I later realised the "ulterior motive" of the pollies. Those bananas created a nice smoke-screen that made the punters relax about accelerating inflation, and the Government was able to dismiss the impact as "not our fault" (if one neglects the impact of Global Warming policy on the severity of cyclones). The smokescreen also allowed a petrol price rise to be smuggled into the CPI on that occassion...

And best of all, the Govt got a nice payback of *deflationary* falls in banana prices some months later when supply got back to normal!
(Now that I think of it, maybe I should send this to the "Hollowmen" as a script idea.)
;-)