3 ms·

How can u get a wrong positive result if you only test correct H1s?

• lisper 9y ago
  Because there is a very long causal chain between raw physical phenomena and your perceptions. Your equipment could be faulty. You could be suffering from hallucinations. You could be a brain in a vat. Example: I want to test if evolution is true. I hypothesize that if evolution is not true, then God will give me some sort of sign, e.g. I pray to God to make a coin that I flip come up heads if evolution is false. I flip the coin and it comes up tails. I conclude that evolution is true. That conclusion would be wrong even if evolution is true.
  • Paradigma11 9y ago
    You are moving into metaphysics and including stuff that is not covered by Null Hypothesis Significance Testing. But on the original point "Likewise, in the long run, using a p threshold of 0.05 (which many journals do) will generate 5% false positive results" is just plain wrong. P(A|B) != P(A)
    • lisper 9y ago
      > P(A|B) != P(A) It is if P(A) is 1, which is what you stipulated when you asked "How can u get a wrong positive result if you only test correct H1s?" > "... using a p threshold of 0.05 ... will generate 5% false positive results" is just plain wrong No, it's not wrong, it just makes a tacit assumption that most hypotheses that get experimentally tested are incorrect. Which is a reasonable assumption. If it were not true, making scientific progress would be a lot easier.