Recent content by Dason

  1. Dason

    Ratio of two random variables squared

    So a few fun facts: A Cauchy distribution is the same as a T distribution with 1 degree of freedom. If you square a T distribution with k degrees of freedom it has the same distribution as a F(1, k) distribution. So F(1,1) is the same as the square of a T with 1 degree of freedom which is the...
  2. Dason

    Ratio of two random variables squared

    Related but not directly the answer is that the ratio of two independent standard normal random variables is Cauchy distributed
  3. Dason

    Sampling Distribution Problem

    Hi! :welcome: We are glad that you posted here! This looks like a homework question though. Our homework help policy can be found here. We mainly just want to see what you have tried so far and that you have put some effort into the problem. I would also suggest checking out this thread for...
  4. Dason

    Difficult understanding this probability problem - help!

    How did you get 10%?
  5. Dason

    Prove binomial from Multinomial

    The starting point would probably be to write out the joint pmf for the multinomial distribution and then figure out what the appropriate sum will look like. What have you tried so far?
  6. Dason

    I made up a counting/probability problem and I'm having trouble thinking about it the right way

    So if there is a 1/625 probability that a particular student gets that teacher 4 years in a row then if we want to find the probability that at least one student gets the teacher 4 years in a row we could first find the probability that a student doesn't get them 4 years in a row (1 - 1/625) and...
  7. Dason

    read.csv adds weird character to my first column header

    A script should be reproducible. You have a specific file in mind for your code - name it explicitly. If your script could apply to more than one file then you can list those or make the rest of the script into a function and call the function on the files of interest. Take my quote to mean...
  8. Dason

    read.csv adds weird character to my first column header

    This looks like an encoding issue to me. Upon playing around with creating different files with different encodings and messing with the headers I think I've found the issue. I'm guessing your file is UTF-8 encoded. The solution is fairly simple. We need to tell R the encoding when reading...
  9. Dason

    Finding E((x-a)^2)

    Keep in mind that 'a' is just a number. What can you do in cases where you have something like E(2X)? Is there anything you can do with that? What about something like E(X+5)? Combine those pieces and it might help you out.
  10. Dason

    Finding E((x-a)^2)

    With the information given and according to common convention 'a' would just be an arbitrary constant. So I would just suggest expanding out (X-a)^2 and then using the typical expectation properties.
  11. Dason

    Fleeting/Random Thoughts

    Calculus through multiple integration is pretty much required. Working with joint distributions requires multiple integration and any program that touches any theory will require that. Linear algebra is needed when you get into the theory for linear models so it's pretty important as well...
  12. Dason

    Help with decision tree when continuous data

    @trinker - we forgot to provide the Kool-Aid
  13. Dason

    Fleeting/Random Thoughts

    It's been almost two years since there has been a post in here? I guess quark's fear that the chatbox would kill some of the activity on the forum wasn't entirely unwarranted...
  14. Dason

    Arch Challenge

    https://wiki.archlinux.org/index.php/KDE
  15. Dason

    Arch Challenge

    Side note: I think it's getting easier to install Arch? Or maybe my hardware situation isn't as complicated. Or I'm just getting better at figuring out these issues. But I didn't really have any issues installing Arch this go around. I tried out KDE and honestly I didn't use to like it but it...