increase by 10% or increase 10%

[yppah]

which one is correct? Thanks.

[BobK]

Both, but they have different meanings; one is relative, the other absolute.

If something is measured at 70% of something else, and increases by 10%, it goes up to 77% - an increase of 10% relative to the original reading.

If something is measured at 70% of something else, and increases 10% it goes up to 80% - an absolute increase of 10%.

Public speakers often confuse these, some would say deliberately. I take a more generous view: I think they just don't understand the difference, and say whichever sounds best.

b

[yppah]

thanks, BobK.

I am still a bit confused. Any other teacher?

[MikeNewYork]

Both, but they have different meanings; one is relative, the other absolute.

If something is measured at 70% of something else, and increases by 10%, it goes up to 77% - an increase of 10% relative to the original reading.

If something is measured at 70% of something else, and increases 10% it goes up to 80% - an absolute increase of 10%.

Public speakers often confuse these, some would say deliberately. I take a more generous view: I think they just don't understand the difference, and say whichever sounds best.

b

Are you certain about that? I have never heard that distinction in medicine.

If I intended your second meaning, I would say increased 10 percentage points.

[BobK]

Are you certain about that? I have never heard that distinction in medicine.

If I intended your second meaning, I would say increased 10 precentage points.

I agree that saying 'percentage points' is a way to make the absolute case clear; that happens in BE too. And a way to make the relative case clear is 'by a factor of 10%' (or .1, if you're being picky, or 1.1 if you're being really picky).

But when people say either '10% increase' or 'increase by 10%' there's the possibility of either meaning, and some people (I think - native speakers of BE feel free to say I'm wrong) make the distinction I've made. Probably (sorry - the language here is fuzzy; the answer to the original question is that in BE they're both acceptable but not interchangeable).

b

[rewboss]

The original question is:

Which is correct? "increase by 10%" or "increase 10%"? (Note the word order.)

The answer is: "increase by 10%", if we assume that "increase" here is a verb. The amount of the increase requires the preposition "by":

The amount was increased by 10%.
The temperature increased by 5°C.
The pressure increased by 0.5hPa.
The voltage increased by 5V.

BobK, you're thinking of "a 10% increase", which is a different case altogether. In that phrase, "increase" is a noun, not a verb, and "10%" has an adjectival function. But that phrase was not in the original question.

[BobK]

Ah so. 'Read the question' - now where have I heard that before?

b

PS - e pur si muove: I'm sure I've heard bosses say things like: 'The figures are 70% of last year. We need to increase those 10% this year' - and they didn't mean 'to 77%'.

[rewboss]

PS - e pur si muove: I'm sure I've heard bosses say things like: 'The figures are 70% of last year. We need to increase those 10% this year' - and they didn't mean 'to 77%'.

Yep, people often say "per cent" when they mean "percentage points". But in the domain of mathematics, that is an error -- and potentially a very serious one.

[BobK]

Yep, people often say "per cent" when they mean "percentage points". But in the domain of mathematics, that is an error -- and potentially a very serious one.

Thanks for the clarification.

b

PS
In another string, Mike said '... in our attempt to create interesting and complex grammar rules to explain this error, I think we forget how easy it is to pick up the language mistakes of others.' I suspect I was creating an interesting and complex grammar rule to justify a simple mistake.

[MikeNewYork]

Thanks for the clarification.

b

PS
In another string, Mike said '... in our attempt to create interesting and complex grammar rules to explain this error, I think we forget how easy it is to pick up the language mistakes of others.' I suspect I was creating an interesting and complex grammar rule to justify a simple mistake.

So are we all in agreement that, considering a base of 70%, an increase of 10% and increased by 10% both produce 77%?