In the path diagram below, free arrows are omitted. How many free arrows should there be, where do they go, and what do they mean? What does the curved line mean? The diagram represents some regression equations. What are the equations? the parameters? State the assumptions that would be needed to estimate the parameters by OLS. What data would you need? What additional assumptions would be needed to make causal inferences? Give an example of a qualitative causal inference that could be made from one of the equations. Give an example of a quantitative causal inference.

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