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Two problems: first is that casual association may be invisible to even hand-waving criteria; think good crypto PRNG output which is fully determined by seed an
by mbq 13y ago
Two problems: first is that casual association may be invisible to even hand-waving criteria; think good crypto PRNG output which is fully determined by seed and is serial number, but the parameters are practically unfittable from the data because the function is so chaotic. Second thing is that the more hand-waving you allow the more totally incidental relations will look "true". With a modern amounts of hypotheses, even Pearson correlation often becomes useless in this manner.
- conjectures 13y agombq, I would not contradict your points. Though first sense 'correlation' could well be useless in many cases at least I know what it means. The second sense is perfidious as it's virtually impossible to deny there's a 'correlation' between any two things since the term so poorly defined.
- mbq 13y agoNote that I am criticising the idea of "general" or "intuitive" correlation; actually useful correlation measures (like Pearson or Spearman) will be just always tied to some model of dependence. This way it cannot be directly tied to the obviously absolute dependence.