dissociated populations and samples! with the 50% case we don't know specifically what a noun is or what a verb is. but we could imagine a population of trying all possible sentences of all possible words ........... uhhhh maybe ?????????
oops! - anywhere somewhere we'll have a list with at least two items in it noun is noun noun is verb and somewhere else we might have a list with at least 4 items in it word_a is noun, word_b is noun word_a is noun, word_b is verb word_a is verb, word_b is noun word_a is verb, word_b is noun - to determine what group we are selecting from, we could propagate information from the purpose of sampling
