Use of "in" or "of the"

Question

In the sentence below would it be grammatically correct the use of "in" before "demand"?

The increase in stress rates has intensified my laughter amount from the increase in demand for job responsibility.

Answer 1

Using "in" before "demand" is just as correct as using "in" before "stress". The part to focus on is "increase in noun phrase", the noun phrases being "stress rates" and "demand for job responsibility".

The phrase "in demand" refers to something being desired. Note the difference between

...the increase in demand for job responsibility

and

...the increase, in demand, for job responsibility

The first one indicates the desire or demand for job responsibility is increasing or has increased. The second one, specifically using the phrase "in demand", indicates that it is the increase itself that is desired or demanded.

As an aside, your example sentence, while not incorrect, is as a whole bit awkward stylistically. It's also hard to tell what exactly you mean. It seems to me you mean something more like:

The increase in stress rates has intensified the amount of my laughter more than the increase in demand for job responsibility.

Another more natural way to say this would be:

The increase in stress rates has made me laugh more than the increase in demand for job responsibility.

The phrase "made me verb" means the same as "caused me to verb". If you wanted to keep the idea of intensity and intensifying in the sentence, I would phrase it like this:

The increase in stress rates has made me laugh intensely more than the increase in demand for job responsibility.

Apologies if I've distorted your intended meaning too much. =P