Results 1 to 4 of 4

Math Help - Probably Plots

  1. #1
    Newbie
    Joined
    Aug 2009
    Posts
    21

    Probably Plots

    If I have a set of data how can I construct a probability plot to see whether the exponential distribution is a good fit for the data?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member Focus's Avatar
    Joined
    Aug 2009
    Posts
    228
    Quote Originally Posted by bubblygirl90 View Post
    If I have a set of data how can I construct a probability plot to see whether the exponential distribution is a good fit for the data?
    You can plot an empirical distribution function and see how much it looks like the cdf of an exponential. I suggest using R, it had a build in function to do this (here is the reference)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Aug 2009
    Posts
    21
    Thanks for the advice but how do I do this in R? Ive just downloaded it but can't seem to figure it out
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member Focus's Avatar
    Joined
    Aug 2009
    Posts
    228
    Quote Originally Posted by bubblygirl90 View Post
    Thanks for the advice but how do I do this in R? Ive just downloaded it but can't seem to figure it out
    The function is called ecdf. It takes a vector as an input and that should be your data. You can check out the documentation and in particular, 5.1 and 7 refer to how to use vectors and input data and 12.1.1 shows how to plot things.

    R is not that easy at first sight but I think it is worthwhile to learn if you want to do statistics. If you use an other piece of software to plot things (or pen and paper) let me know and I can be a bit more helpful.

    You could also use for example Pearson's chi square test to determine how well your data fit an exponential (which again R has built in).
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Polar Plots
    Posted in the Calculus Forum
    Replies: 3
    Last Post: September 25th 2011, 06:28 AM
  2. Log-Log plots!!
    Posted in the Calculus Forum
    Replies: 0
    Last Post: November 9th 2009, 11:38 AM
  3. PLEASE HELP Box and Whisker Plots
    Posted in the Statistics Forum
    Replies: 1
    Last Post: August 11th 2009, 07:39 PM
  4. Residual plots.
    Posted in the Statistics Forum
    Replies: 5
    Last Post: June 27th 2009, 11:47 PM
  5. implicit plots on TI-92
    Posted in the Calculators Forum
    Replies: 0
    Last Post: July 30th 2007, 02:30 PM

Search Tags


/mathhelpforum @mathhelpforum