That's not what Yule-Simpson implies. They're missing the data breakdown by school, so you can't make the conclusion that somehow they're lying instead. Again,

That's not what Yule-Simpson implies. They're missing the data breakdown by school, so you can't make the conclusion that somehow they're lying instead. Again, they don't make a conclusion and you can't either. In the absence of that school-centered data, it is reasonable to come to their conclusions on the national data set.