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Math Help - Graphing the probability distribution function.

  1. #1
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    Graphing the probability distribution function.

    Hi,

    A quick question, if I have a uniform random variable X with a range (1,2,3,...,n) and mass function given by

    Px(i) = 1/n

    For i=1,2,3,...,n.

    What does the graph of the probability distribution function Fx actually look like?

    Hopefully it's easy to describe...

    Edit:

    I know it's piecewise constant. It takes the value of 0 for x<1.
    and then jumps to a value of 1 at x=1. Does it then jump by 1/2 at x=2 and jump by 1/3 at x=3 so on?
    Last edited by waynex; March 31st 2010 at 05:54 AM.
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  2. #2
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    Quote Originally Posted by waynex View Post
    Hi,

    A quick question, if I have a uniform random variable X with a range (1,2,3,...,n) and mass function given by

    Px(i) = 1/n

    For i=1,2,3,...,n.

    What does the graph of the probability distribution function Fx actually look like?

    Hopefully it's easy to describe...

    Edit:

    I know it's piecewise constant. It takes the value of 0 for x<1.
    and then jumps to a value of 1 at x=1. Does it then jump by 1/2 at x=2 and jump by 1/3 at x=3 so on?
    Dear waynex,

    Since this is a probability distribution function it is not continuous. Please refer to the attachment. Of course the points goes on until i=n.

    Hope this will help you.
    Attached Thumbnails Attached Thumbnails Graphing the probability distribution function.-sp1.png  
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  3. #3
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    Thanks a million for your reply. Quite literally all we have in the notes regarding the graphing of the pdf is:

    Fx can be described in words as follows: it is a right-continuous step
    function which increases by jumps of size p_j located at x_j , j = 1, 2, . . .
    So I guess you can see where I came up with my answer in the edit above, so I would have thought that it would increase.

    So the value at x_2 in the problem above would be 1/2 and not 1+1/2 is that correct?

    Thanks again.
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    Quote Originally Posted by waynex View Post
    Thanks a million for your reply. Quite literally all we have in the notes regarding the graphing of the pdf is:



    So I guess you can see where I came up with my answer in the edit above, so I would have thought that it would increase.

    So the value at x_2 in the problem above would be 1/2 and not 1+1/2 is that correct?

    Thanks again.
    Dear waynex,

    Yes it is correct. Hope you have understood the ideas clearly.
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