Recent content by mynameisfunk

  1. M

    Is a model nested with itself before collapsing categorical variables?

    If I have a model with a categorical variable X1=0,1,2,3 and a continuous variable X2 and I have a regression model that includes an interaction between X1 and X2, then I decide I want to collapse X1 into an indicator variable where X1_new=0 if X=0 and X1_new=1 if X>=1, is my new model with an...
  2. M

    Calculating P(Y<$\sqrt{X}$) for Joint PDF of X and Y

    Here is the picture I drew. Am I not drawing this right?
  3. M

    Calculating P(Y<$\sqrt{X}$) for Joint PDF of X and Y

    I want to add to this post. Sorry for the double posting. I know this solution I posted above can't be right. I tried switching the order of integration from dydx to dxdy and I get 1/3. One of my classmates suggested doing a bivariate transformation, which I haven't tried but I am a little...
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    Calculating P(Y<$\sqrt{X}$) for Joint PDF of X and Y

    Homework Statement Suppose that the joint pdf of X and Y is f(x,y)= (8/3)xy , 0<x<1,0<y<2, x<y<2x Compute P(Y<\sqrt{X}) Homework EquationsThe Attempt at a Solution \int_0^1 \int_x^{\sqrt{x}} (8/3)xy dy dx = (4/3) \int_0^1 x - x^2 dx = 2/9
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    Example of Probability Distribution Not in Exponential Family

    Is there a good example of a probability distribution where the support set does not depend on the parameters and is still not a member of the exponential family?
  6. M

    Expected Value (joint pdf)

    thank you! OK, thanks for that. OK, just to be clear, can you tell me if this looks right? [ itex ]E[X|Y=5] = \int_{0}^{10} x E[X|Y=5] dx \int_{0}^{1} x * 1/5 dx = \left[ \frac{10}{2}x^2 \right]_{0}^{10} = 10[ /itex ] Not sure why I can't get this latex to work but I am getting 10 for...
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    Expected Value (joint pdf)

    Homework Statement A machine consists of 2 components whose lifetimes are X and Y and have joint pdf, f(x,y)=1/50 w/ 0<x<10, 0<y<10,0<x+y<10 Calculate the expected value of X given Y=5. Homework Equations E[X|Y]= \int_{-inf}^{inf} x f(x,y)/f(y) dx The Attempt at a Solution...
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    Lottery probability Question

    Homework Statement Euromillions is a transnational lottery. A player selects 5 "main" numbers without replacement, ignoring order from 1 to 50. The player then selects 2 "lucky star" numbers without replacement and ignoring order from 1 to 11. Ultimately, 5 numbers are randomly selected...
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    Multiple Random Variable Question

    Homework Statement A and B agree to meet at a certain place between 1 PM and 2 PM. Suppose they arrive at the meeting place independently and randomly during the hour. find the distribution of the length of time that A waits for B. (If B arrives before A, define A's waiting time as...
  10. M

    Chance of Game Ending in 5 trials: Exam Question Analysis

    Ok guys, maybe you are right. I can see it now. If you were a professor, would you yield? I definitely see an ambiguity here. I just feel like it could have been much clearer as with these questions the wording needs to be pretty clear on what they want. In direct response to Zafa Pi, I...
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    Chance of Game Ending in 5 trials: Exam Question Analysis

    Ok, This is not a homework or textbook problem; this is a question from an exam I recently took that I would like opinion on the wording of the problem. Question: A fair coin is flipped until a head is observed and then a fair die is rolled until a 6 appears. Each flip and each roll is...
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    Career Statisticians: Masters in Data Mining Marketability

    Chiro, thanks for the input. I don't really have a whole lot of options as far as moving to another city to enter into a much better program because I am not single and have a son. However, I would really like to break into the field and I feel like I need a master's degree to do it. I...
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    Career Statisticians: Masters in Data Mining Marketability

    I am curious for the opinion of career statisticians on how marketable a Masters in Data Mining would be. I am currently a high school math teacher who has a degree in Economics. In college I had intended to pursue grad studies for statistics and have some SAS programming experience as well as...
  14. M

    What is the equation of a line given one point and another unknown value?

    Had a SAT level geometry question from a student and didn't know how to solve it. I redrew what the picture was and the question asked for the slope. I know PF better than that but don't just give me the answer bc I need to know how to solve.
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    Is it common for people to drink tea/coffee to boost their performance?

    Works for some people... http://en.wikipedia.org/wiki/Paul_Erd%C5%91s
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