Serving the Quantitative Finance Community

 
User avatar
mahalekrishna
Posts: 0
Joined: March 29th, 2009, 4:04 pm

Prove that Y1 and Y2 are independent

April 2nd, 2009, 10:12 pm

QuoteOriginally posted by: PdISince the event{X₁+X₂=y₁,X₁/(X1+X2)=y₂}is equivalent with the event{X₂=y₁(1-y&#8322,X₁=y₂y₁}we obtain for the densityf(y1,y2)=exp(-y1*(1-y2))*exp(-y1*y2) =exp(-y1)yikes.. you transformed the space (plane) without accounting for the jacobian
 
User avatar
PdI
Posts: 0
Joined: March 17th, 2009, 12:05 am

Prove that Y1 and Y2 are independent

April 3rd, 2009, 9:13 am

You right, the Jacobian is abs(det[y2 y1;1-y2 -y1 ])=y1 so you get f(y1,y2)=y1*exp(-y1)