conditional probability

  1. C

    Probability Question (Ambiguous)

    SOLVED BY MYSELF, YOU CAN CLOSE THE THREAD :) Hi guys, I'm new to this forum, and some of you might find it annoying that I post a question straight off, but the assignment is due tomorrow and I have two different answers. I do promise to keep posting in threads (when I have something to say)...
  2. Y

    Difference between p(y=0|x=0) and p(x=0,y=0)

    Another Trivial question: I have been asked to calculate the joint probability i.e. p(X=0,Y=0) and i have been provided by P(Y=0|X=0), is it the same?
  3. S

    Conditional probabilities when trading options and forecasting

    Dear Statistics-Gurus, I am trying to figure out how to "combine" two dependent probabilities, namely the probability to forecast the market direction wrong P(wrongFC)=35% and the probability of an option to be in-the-money ITM (only if the option is ITM I am losing money). The option can...
  4. T

    Sample size sensitivity in time series regression analysis

    I have a time series that I've built a regression on, say Y = X + Y. For a data set of size 300, the coefficients of X and Y are statistically significant. But, the coefficients are not statistically significant for a (sequential) subset of the dataset of, say, 150 points. Now, since the...
  5. J

    Conditional probability problem

    Hey all, I hope you can help me with this problem. Say that tomorrow I can go to Berlim with a probability of 20%, Madrid with a probability of 10% or New York with a probability of 5% (or stay home with prob of 65%). Then, what is the probability that tomorrow I go to one of those cities...
  6. V

    Estimating parameter from conditionals of non-independent data

    The context of this problem is the estimation of the distribution of a parameter v given sets of data A and B, where A and B are not independent. Suppose I know P(v | A) and P(v | B). Both of these distributions are definitely not normal (the answer should not make any assumptions about the...
  7. M

    52 card deck

    Ok, I have been trying to solve part d) in my homework for the past hour and then I turned to the web and still couldn't find an answer. This is an advanced probability and statistics class and I am willing to work hard but I don't know how to do everything. I have solved a, b, and c. The...
  8. H

    Probability with sampling question

    i have been having problems with what should be a trivial probability problem Suppose there are 130 patients. Each patient was administered one of 6 drugs as follows: Drug A: 25 patients Drug B: 31 patients Drug C: 13 patients Drug D: 17 patients Drug E: 28 patients Drug F: 16...
  9. H

    2 four sided dice, probability of 1 dice = 3, sum = even

    [Question] 2 four tetrahedral dice with sides, 1,2,3,4. the two dice are thrown, what is the probability that given the first dice is a 3, the sum of the 2 dices will be an even number. This has had me stumped for about 30mins. im assuming i should be using P(A|B) = P(A&B)/P(B) where...
  10. M

    Disease Probability

    I'm stuck on a question. A doctor thinks, before testing, that the probability that his patient has XYZ disease is 85%. He tests 5 times and gets 3 positive tests and 2 negatives. When a patient does have XYZ, they test positive 70% of the time. Patients who do not have XYZ test positive...
  11. L

    Probability assignment

    Let Y be binary variable P(Y = 1) = P(Y = 0) = 0.5 and X a random variable uniform on [0,5] when Y = 0 and uniform [4, 9] when Y = 1. Draw mean of X and P(Y = 1|X = x) as functions of x. What is the minimum probability of rejection to predict Y from X without mistake. This is my attempt to...
  12. S

    expectation of conditional probability

    Hi there, I have two questions which I found answers to slightly different version of them in books but not to those that I have in mind so please pay attention in responding. 1) I like to calculate the expectation of conditional probability Pr(X|Y) for all values of Y. Meaning I want to...