Which is correct?

English as a Second Language English Vocabulary, Grammar and Idioms
1

We need to adjust the forecast based on the old rates.
We need to adjust the forecast for the old rates.
Which is correct?

We need to adjust the forecast based on the then higher prices.
We need to adjust the forecast for the then higher prices.
Which is correct?

How do we use “adjust for” ? What does it mean?

Thanks

2

Hi,

I would suggest that ‘based on’ and ‘based on the then …’ are the preferred choices to make the point clearly.

‘Adjust for’ suggests that you change something in order to take into account something new.

Alan

3

Either of them could be correct depending on the meaning you wish to convey.

based on - using the old rates /the higher prices as a basis for the adjustments.
for the - in order to include the old rates / higher prices.

adjust something for - make adjustments for a particular aspect of something:
My wedding dress is too big. We will have to adjust it for size. - the adjustment is to the size, not the colour, style, etc.
I cannot think of a use of ‘adjust for’ without the noun or pronoun between the two words, other than a rewording of the above:
My wedding dress is too big. It will have to adjusted for size.