2 ms·

What's the difference?

• DavidSJ 15y ago
  It's the same as the difference between "0.1% of non-spam messages are marked as spam" (false positive rate) vs. "0.1% of messages marked as spam are not spam" (false negative rate).
  • prodigal_erik 15y ago
    Those seem like the same false positive case to me. For a false negative, did you mean "0.1% of spam messages are not marked as spam"?
    • DavidSJ 15y ago
      Whoops, you're right, they're both false positives, but one is number of false positives as a percentage of messages marked as spam, and the other is number of false positives as a percentage of messages that aren't spam. The ratios would be completely different.
      • prodigal_erik 15y ago
        Oh yeah, there's only one absolute number of false positives, but when you turn it into a rate you have to choose either "of all positive results, what portion were false" or "of all test results, what portion were positive and false", which are far apart for tests that give many negative results.