Recent content by Mogarrr

  1. Mogarrr

    Prove Chi Square is Stochastically Increasing

    Ok, there is a relationship between the Gamma and Poisson distribution. Let X \sim Gamma(\alpha, \beta) , then P(X \leq x) = P(Y \geq \alpha) , where Y \sim Poisson(x/\beta) . Now let p > q , p,q \in \mathbb{Z}^{+} a>0 , then P(X^2_{p} > a) < P(X^2_{q} > a) \Leftrightarrow P(Y > p) < P(Y...
  2. Mogarrr

    Prove Chi Square is Stochastically Increasing

    Oops. Should have written X^2_{n} = \sum^{n}_{i=1} Z^2_{i} . I was thinking that since the Z_{i}'s are identically distributed, that I could just sum up their squares, X^2_1 . Why am I wrong here, if they're identically distributed? I will try the direct method, since X^2_{p} \sim \Gamma(p/2...
  3. Mogarrr

    Prove Chi Square is Stochastically Increasing

    Based on your hint, here's what I'm thinking... Well, then, if Z_{i} \sim N(0,1) (and i.i.d.) , and X^2_{n} = \sum_{i=1}^{n} Z_{i} , then X^2_{p} = pZ^2_1 and X^2_{q} = qZ^2_1 . Thus for all a , P(X^2_{p} > a) = P(pZ^2_1 > a ) = P(Z^2_1 > \frac {a}{p}) \geq P(Z^2_1 > \frac {a}{q}) =...
  4. Mogarrr

    Prove Chi Square is Stochastically Increasing

    Homework Statement Prove that the X^2 distribution is stochastically increasing in its degrees of freedom; that is if p>q, then for any a, P(X^2_{p} > a) \geq P(X^2_{q} > a), with strict inequality for some a. Homework Equations 1.(n-1)S^2/\sigma^2 \sim X^2_{n-1} 2.The Chi squared(p) pdf is...
  5. Mogarrr

    Crafting Effective Emails to Research Mentors for Summer Internships

    Since I couldn't find any publications by a few mentors, I decided to test "contacting a mentor", by simply introducing myself, stating my research interests, my interest in their project, and asking whether my interests were related to their project. I tried this with one mentor, emailing them...
  6. Mogarrr

    R language, seq and rep problem

    Homework Statement Using rep() and seq() as needed, create the vector 1 2 3 4 5 2 3 4 5 6 3 4 5 6 7 4 5 6 7 8 5 6 7 8 9 Homework EquationsThe Attempt at a Solution I figured out that seq() only takes numbers for the 'from' and 'to' arguments, since I tried seq(seq(...)). Also, I'm not...
  7. Mogarrr

    Crafting Effective Emails to Research Mentors for Summer Internships

    That sounds good. Thanks for the idea.
  8. Mogarrr

    Crafting Effective Emails to Research Mentors for Summer Internships

    Greetings forum-goers, I am planning to apply for a DHS summer internship, where I am encouraged to contact research mentors (although it's stated that OSRI makes the hiring decision). I plan on cold emailing several mentors and, besides introducing myself and mentioning how I am interested in...
  9. Mogarrr

    Biostatistics, help deciding on a test

    I have an exact test for small samples, however I wanted to talk about one more thing concerning this problem. I just learned that McNemar's test can be viewed as a within Chi-Squared Test. Do you think this data is an example of a within-subject design?
  10. Mogarrr

    Contingency Table Interpretation

    Homework Statement 10.24 Is there any relationship between the type of treatment and the response? What form does the relationship take? Here's that data (column variables are responses): \newcommand\T{\Rule{0pt}{1em}{.3em}} \begin{array}{|c|c|c|c|c|} \hline Treatment & +Smear &...
  11. Mogarrr

    Biostatistics, help deciding on a test

    Homework Statement Refer to Table 2.11. 10.6 What significance test can be used to assess whether there is a relationship between receiving an antibiotic and receiving an antibiotic culture while in the hospital? Here's my attempt of recreating the table: \newcommand\T{\Rule{0pt}{1em}{.3em}}...
  12. Mogarrr

    Connected Sets and Their Interiors: Baby Rudin Exercise 2.20 Example

    Thanks guys. Actually, I switched the example to 2 closed balls that just touch each either in \mathbb{R}^2 and to show this was connected, I just looked at a line that intersects the disconnections, and then showed how there can't be a disconnection there.
  13. Mogarrr

    Connected Sets and Their Interiors: Baby Rudin Exercise 2.20 Example

    Then, I'd have to show the closed circle in \mathbb{R}^2 is connected. But I'm not really sure how to do that? I suppose a proof by contradiction, assuming the closed circle is disconnected... (that's pretty much the only technique I got when it comes to connected sets). I suppose if any 2 of...
  14. Mogarrr

    Connected Sets and Their Interiors: Baby Rudin Exercise 2.20 Example

    Homework Statement This is from Baby Rudin Exercise 2.20- Are closures and interiors of connected sets always connected? (Look at subsets of \mathbb{R}^2 ). Homework Equations The interior is the set of all interior points for a set E that is a subset of a metric space X. A subset Y of a...