2 X Y, . P P , .
(, ) p(, ) , . , X Y.
, , p(, )=P P .
Cov(X, Y)=M((X-MX)(Y-MY)), ..
ρ(X, Y) X Y, ρ(X, Y)= , DX, DY X Y. , . , : . - , -1 +1.
, X Y , F(x) , Y=F(x). , , , .
( ). : Y=aX+b, a b .
, X Y , . , ρ(X, Y)=1 ρ(X, Y)=-1. 1< ρ(X, Y)<1, , , a b .
, F(a,b)=M((YaXb) ) a, b . aX+b Y.
, a b :
a= ρ(X, Y) , b=MY ρ(X, Y) MX
F(a,b)=DY(1 ρ(X, Y) ).
1. ρ(X, Y)>0, .
2. ρ(X, Y) <0, .
3. ρ(X, Y)=0, a, b M((Y aX b) )≥DY. , a, b aX+b Y , MY( Y).
4. 1< ρ(X, Y)<1, a,b M((YaXb) )= DY(1 ρ(X, Y) ). , aX+b Y, MY, , .
5. ρ(X, Y)=1 ρ(X, Y)= 1, Y=aX+b 1.
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:
m =MX, m =MY, =Cov(X,Y), =DX, =DY.
, :
F(a,b)= M(Y aX b) =M((Y m ) a(X m ) + (m a m b)) = +a 2a +(m a m b) .
. :
(a,b)=2a 2 2 m (m a m b)=0
(a,b)=2(m a m b)=0
a, b, : a= , b= m m . F(a,b)=2( + )da +4 m dadb+2db =2 da +2(m da+db) >0. . , M(Y aX b) : y=ax+b Y, OY.
.
, .
() , .
: - .
, ( ).
, , :
X ≤ X ≤ ≤ X
:
.
DX ( )
. :
1.
2.
3.
: , .
: . , M =a, M =σ .
M =M = =a.
,
M = ,
:
= = =
, MX = σ +a , M (X X )=MX MX ( X X )
= σ +a ) =(1 ) σ , M =σ .
. D :
D = → 0.
D M → 0, x.