This is the complete form, that is to say, this is it.

Example:

To some extent, this is the reason for the meeting.

To some extent, this is why this meeting was held.

I'm not saying that this is what is happening.

I didn't say it was true. In that case, we need more staff.

In that case, we need more employees.

In that case, we need more staff.

If so, then we need more employees.

This is not the way to treat another person.

That is by no means the way to treat others.