Results 1 to 4 of 4

Math Help - Quick Notation Question

  1. #1
    Member
    Joined
    Mar 2009
    From
    Alberta
    Posts
    173

    Quick Notation Question

    I had to miss class today due to another engagement and in learning what I missed on Bivariate Probability Distributions I've come across this notation.

    f_{XY}(x,y)

    Is this another notation for a function of two variables or does it denote partial derivatives?

    f_{XY}(x,y)=f(x,y)?
    or
    f_{XY}(x,y)=\frac{d}{dx}\frac{d}{dy}f(x,y)?

    Or something else?

    Thanks for the clarification!

    Kasper
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor harish21's Avatar
    Joined
    Feb 2010
    From
    Dirty South
    Posts
    1,036
    Thanks
    10
    f_{XY}(x,y) denotes the joint probability distribution of two continuous random variables X and Y.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Mar 2009
    From
    Alberta
    Posts
    173
    Quote Originally Posted by harish21 View Post
    f_{XY}(x,y) denotes the joint probability distribution of two continuous random variables X and Y.
    Oh, k. Thanks!
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor matheagle's Avatar
    Joined
    Feb 2009
    Posts
    2,763
    Thanks
    5
    These are not partial derivatives.
    We use the subscripts since one bivariate density generates 4 more densities, the two marginals and the two conditionals.
    Thus, there are five densities and we use f for all five.
    The subscripts "differentiates" an excellent pun, which density is which.
    BUT there is no differentiation here at all.
    NOW, f is the derivative of F, the cdf........
    Last edited by matheagle; October 19th 2010 at 11:01 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Two quick questions on the 'differential' notation
    Posted in the Differential Geometry Forum
    Replies: 14
    Last Post: August 7th 2011, 02:17 AM
  2. A Quick Question on Valid Set Builder Notation
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: July 7th 2011, 12:10 PM
  3. Replies: 1
    Last Post: January 23rd 2011, 12:07 AM
  4. Quick Question about Vector Notation
    Posted in the Calculus Forum
    Replies: 2
    Last Post: September 22nd 2009, 07:45 AM
  5. Quick question about notation
    Posted in the Statistics Forum
    Replies: 3
    Last Post: December 16th 2007, 10:24 PM

Search Tags


/mathhelpforum @mathhelpforum