Chapter 7 of my book introduces the term “Simultaneous Census” which is nothing more than a more specific description of what the “true value” in a poll is.
Why do we need it? Well, currently, there are two different ''“true values” used by the field's analysts - which depends on their country's tradition - and both are unscientific (and wrong)
What do polls (try to) measure? Answer: a simultaneous census