Passage Summary: We can guess how many teachers we'll need based on how many babies are born, but those guesses get worse as we try to predict specific subjects like jazz music.

Reasoning: General demand for professors is accurately predicted by birth rates, but this accuracy drops when looking at specific fields like music, and drops even further for sub-fields like jazz.

Analysis: This stimulus describes a clear trend: as the scope of a group narrows, the predictive power of a general demographic indicator weakens. The principle we are looking for should reflect this relationship between the size of a category and the reliability of a prediction. It suggests that while broad trends might apply to a whole population, they are less dependable when applied to smaller, more specialized subgroups. Look for an answer that abstracts this 'broad vs. specific' dynamic.