Re: Question on Conditional PDF

2002-02-25 Thread Glen Barnett


Chia C Chong [EMAIL PROTECTED] wrote in message
a5d38d$63e$[EMAIL PROTECTED]">news:a5d38d$63e$[EMAIL PROTECTED]...


 Glen [EMAIL PROTECTED] wrote in message
 [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
  Do you want to make any assumptions about the form of the conditional,
  or the joint, or any of the marginals?

 Well, the X  Y are dependent and hence there are being descibed by a joint
 PDF.

This much is clear.

 I am not sure what other assumption I can make though..

I merely though you may have domain specific knowledge of the variables and
their likely relationships which might inform the choice a bit (cut down the
space
of possibilities).

Can you at least indicate whether any of them are restricted to be positive?

Glen




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Re: Question on Conditional PDF

2002-02-25 Thread Chia C Chong


Glen Barnett [EMAIL PROTECTED] wrote in message
a5dev7$8jn$[EMAIL PROTECTED]">news:a5dev7$8jn$[EMAIL PROTECTED]...

 Chia C Chong [EMAIL PROTECTED] wrote in message
 a5d38d$63e$[EMAIL PROTECTED]">news:a5d38d$63e$[EMAIL PROTECTED]...
 
 
  Glen [EMAIL PROTECTED] wrote in message
  [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
   Do you want to make any assumptions about the form of the conditional,
   or the joint, or any of the marginals?
 
  Well, the X  Y are dependent and hence there are being descibed by a
joint
  PDF.

 This much is clear.

  I am not sure what other assumption I can make though..

 I merely though you may have domain specific knowledge of the variables
and
 their likely relationships which might inform the choice a bit (cut down
the
 space
 of possibilities).

 Can you at least indicate whether any of them are restricted to be
positive?


All values of X and Z are positive while Y can have both positive and
negative values.
In fact, X has the range span from 0 to 250 (time) and Y has values that
span from -60 to +60 (angle) and Z has some positive values. Note that, the
joint PDF of X  Y was defined as f(X,Y)=f(Y|X)f(X) in which f(Y|X) is a
conditional Gaussian PDF and f(X) is an exponential PDF. The plot of the 3rd
variable, Z (Power)  i.e. Z vs X and Z vs.Y, respectively shows that Z has
some kind of dependency on X and Y, hence, my original post was asking the
possible method of finding the conditional PDF of Z on both X and Y. I hope
this makes things a little bit clearer or more complicated???


Thanks..

CCC

 Glen






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