# Learn English – Increase or increase by?

prepositions

I wonder which is correct:
The added value obtained per ha is increased by 2.7 times with irrigation
or
The added value obtained per ha is increased 2.7 times with irrigation

These sorts of statements are destined to cause confusion. The source is that it's never quite obvious whether you mean it's increased to 2.7 times it's previous value, or it's had that amount added to it.

For example, if we started with 100, does it mean

A) it was at 100 before, and it's increased to 2.7 times its previous value, so it's now 270?

B) Or, does it mean that we multiply 2.7 by 100, and then it's increased by that amount, making it a total of 370 now?

Regardless of what you, the writer think, some people will interpret it the first way and some the second. Possibly one group is simply wrong, but that doesn't really make any difference: it's failed as a piece of writing if it causes confusion like this. Sometimes people (eg advertising copy writers) will exploit this confusion to trick people into thinking some statistic is more impressive than it really is.

To avoid this problem, I would always say it has "increased to 2.7 times its previous value". This makes it clearer that it's option A, above. It's good form to put the actual numbers in too, if possible.