The longer you spend in any one country, the more likely you are (the comma)

[Nonverbis]

This is from Upstream Pfoficiency by Virginia Evans and Jenny Dooley.

Could you tell me whether a comma is missing here?

 

[Tarheel]

In my opinion, no. (Others may disagree.)

The longer the sentence is the more likely you are to need a comma. However, the length of the sentence is not what determines that. (Note that my sentence (the first one) is only four words long.)

 

[Nonverbis]

I can't catch your idea.

This is from the book "Practical English Usage" by Michael Swan. And here we have a lot of short sentences. But sometimes a comma is used, and sometimes not.

Is there any rule?

 

[Tarheel]

A good rule of thumb is if you would pause in speech you put a comma there.

 

[Nonverbis]

A good rule of thumb is if you would pause in speech you put a comma there.

I can't agree with you.

This is "The Penguind Guide to Punctuation":

 

[jutfrank]

Yes, there really ought to be a comma there.

(By the way, the writer of the Penguin guide is hopelessly wrong. It is generally a very good rule of thumb.)

 

[Tarheel]

A good rule of thumb is if you would pause in speech you put a comma there.

I can't agree with you.

This is "The Penguind Guide to Punctuation":

View attachment 4713

I assume (perhaps wrongly) that you mean you don't agree with me.

After 70 years, I'm not likely to change my opinion now.