3 ms·

Show HN: If Correlation doesn't imply causation, then, what does?

• xaedes 6y ago
  "For the notion of causality to make sense we need to constrain the class of graphs that can be used in a causal model. Obviously, it’d make no sense to have loops in the graph: We can’t have X causing Y causing Z causing X! At least, not without a time machine. Because of this we constrain the graph to be a directed acyclic graph, meaning a (directed) graph which has no loops in it." Of course you can have loops, no need for time machine: https://en.wikipedia.org/wiki/Virtuous_circle_and_vicious_circle https://en.wikipedia.org/wiki/Virtuous_circle_and_vicious_ci... https://en.wikipedia.org/wiki/Causal_loop_diagram https://en.wikipedia.org/wiki/Causal_loop_diagram https://en.wikipedia.org/wiki/Positive_feedback https://en.wikipedia.org/wiki/Positive_feedback
  • spot5010 6y ago
    The examples you have posted do not contradict what the author is saying. A feedback cycle is something like: a quantity A at time t1 given by A(t1) influences another quantity B(t2) which in turn influences A(t3). Here t3 > t2 > t1. We would run into causality issues if t3 = t1, but that doesn’t happen.
  • jobigoud 6y ago
    In your examples X and Z are events of the same kind but not the same event.