PatrThom wrote:The ones that always get me are statements like:

"The new version is three times smaller than the old one."

Ergargleblarg that's not possible! It can be "67% smaller" or "1/3 the original size," but saying something is "twice as slow" is about as useful as saying your magical device can amplify sound on the order of one to the fourth power.

Like most things that pedants rant about on the internet, this is an accepted (by most) feature of English, is technically correct when viewed appropriately, and is only a problem when it causes ambiguity or awkward constructions.

It turns out that we can measure slowness. There's even a unit for it, known as the second. If one thing is twice as slow as another, then it takes twice as many seconds to complete.

Similarly, you can measure speed, in meters per second or in hertz. Something twice as fast moves twice as many meters per second, or accomplishes twice as many things per second (or other time interval). If one thing is twice as fast as another, it takes half the time to complete.

This isn't really even a problem for "three times smaller", because in vernacular English this almost certainly means the same as "three times as small". When "smallness" is measured appropriately (e.g. the number of items you can fit in a manila envelope), then this object has three times as much smallness as the previous version (and not four times as much).

The only times this is a problem is when the difference is less than 100%, and the direction isn't clear from the measurement; or when people say "x% faster" but mean "x-100% faster". For example, a car that's 25% faster probably moves 25% more meters in one second at top speed, but it might instead reach some particular speed (60mph?) in 25% fewer seconds, or have 25% higher acceleration at some speed, or something. Similarly, a computer program that's 25% faster might complete in 25% less time. Or it might compute at 25% more effective FLOPS, which would cause it to complete in 20% less time.