Re: mutually exclusive vs independent
- From: "Ethan.Johnsons@xxxxxxxxx" <Ethan.Johnsons@xxxxxxxxx>
- Date: 14 Sep 2006 19:20:27 -0700
thx so much all. it is a great help.
ej
Bruce Weaver wrote:
Ethan.Johnsons@xxxxxxxxx wrote:
So, "independent" can have the overlapping area in Veen diagram,
correct?
More than that. They HAVE to overlap in a Venn diagram. If events A
and B are independent, p(A) = p(A|B), and p(B) = p(B|A). In other
words, knowledge that B has happened does not affect p(A); and knowledge
that A has happened does not affect p(B).
In your Venn diagram, if it is drawn to scale:
p(A) = area of circle A over total area
p(B) = area of circle B over total area
p(A|B) = area of A-B intersection over area of circle B
p(B|A) = area of B-A intersection over area of circle A
So, for p(A) to equal p(A|B), and for p(B) to equal p(B|A), there has
to be overlap, and it must be in the correct proportions.
Then, what is "dependent"?
Not independent. Related.
thx much
Reef Fish wrote:
Ethan.Johnsons@xxxxxxxxx wrote:
I thought I understood this, but getting back to me again.The simplest mnemonics for the DIFFERENCE between the two concepts is
Can you pls explain 'mutually exclusive' vs 'independent' for me with
examples if possible?
that THEY are mutually exclusive, i.e., they cannot both happen!
A and B are mutually exclusive if A intersect B is the empty set,
hence
P(A and B) = 0.
If A and B are non-empty events, the they are independent IF and ONLY
IF
P(A and B) = P(A) * P(B)..NE. zero.
-- Reef Fish Bob.
--
Bruce Weaver
bweaver@xxxxxxxxxxxx
www.angelfire.com/wv/bwhomedir
.
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