Causal Models

Abstract

Sometimes Y can be forecast by knowing X. For example, it is possible to forecast fairly accurately how fast a brick will travel (Y) if dropped from a height (X). The important assumptions here are that 1) X causes Y (speed) to happen, 2) the relationship (law, theory) between X and Y is known, and 3) X (height) has been measured accurately. There is a strong causal connection between dropping the brick and its speed, i.e., gravity. After many years of measurement, debate, mathematics, and testing of the laws of gravity, it is now generally accepted that in all cases if a brick is dropped it will fall towards the ground with a calculable speed (ignoring very low probabilities!).