8
$\begingroup$

This is more of a historical question: who invented the notation $\perp \!\!\! \perp$ for denoting (conditional) independence?

| cite | improve this question | | | | |
$\endgroup$
  • 5
    $\begingroup$ To whom it may concern, this question seems to be on-topic. We have many questions on (history of) notation in probability & statistics, and a tag for them notation. $\endgroup$ – Tim Dec 6 '18 at 8:07
  • $\begingroup$ So the tiny orthogonal vectors ⊥ mean marginal independence and with two vertical lines it's conditional independence? $\endgroup$ – suckrates Dec 6 '18 at 8:15
6
$\begingroup$

I have often seen it associated with AP Dawid 1979, "Conditional Independence in Statistical Theory." For example page 373 of these notes. I have no idea if Dawid actually invented it or popularized it.

Update 8/17/19: According to Wikipedia, the symbol was introduced by Elfving: "Elfving introduced the statistical symbol for probabilistic independence ⊥⊥, which is a stronger condition than orthogonality ⊥, by the 1950s."

| cite | improve this answer | | | | |
$\endgroup$
  • 2
    $\begingroup$ In the 'handbook of graphical models' by Maathuis ea it is written explicitly by Milan Studeny "The author of this chapter was told that the conditional independence symbol $\perp \!\!\! \perp $ was proposed by Dawid and Mouchart in their discussion in the late 1970s" $\endgroup$ – Sextus Empiricus Dec 12 '18 at 11:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.