poisson

  1. J

    Poisson Conditional Probability Question

    Hey Guys I've been racking my brain for ages trying to solve this but I can't seem to get the last step. The question is, given 0<u<t , 0<=k<=n Show that P(X(u) = t | X(t) = u) = (n choose k) (u/t)^k (1-(u/t))^(n-k) I have started by using the law of total probability in that P(A|B) =...
  2. M

    Test the fit of rate data to a Poisson process

    How can you test the whether a collection of rate data is consistent with a Poisson process? I am investigating a random process which conceptually could be a Poisson process. I have a collection of rate data (counts/min), and I would like to test whether their distribution is consistent with...
  3. Y

    Poisson

    The number of pacients that get into the hospital is 36 per day. Wich is the probability that in one hour 4 pacients get in.
  4. A

    Gamma Poisson Mixture with finite Gamma

    Dear all I am working with a Gamma-Poisson mixture distribution where (and this is not usual) the support of the Gamma distribution (in fact, I am able to restrict to the neg exponential instead of the Gamma...) is finite, e.g. [0,1]. I would like to derive the mean and a Likelihood...
  5. U

    Help on count dependent variable

    Hello! I am new to this forum. I am bombarded by a lot of info on count DVs. Here are my variables: a. DV= firm-year observations. 7 years, 101 firms. I recorded the number of actions of a firm per year. The resulting measure is a Herfindhal-type of index since I measured the proportion of...
  6. I

    SPSS – Problem with Poisson Model for Rates

    Dear all, I have recently been given a piece of SPSS-based coursework, and with the deadline coming into view I am stuck on the data entry section. I have been given two tables of data: Table 1 presents the number of cases of insulin-dependent diabetes mellitus (IDDM) by sex, age and...
  7. M

    How to prove that the expectation and variance of a Poisson random variable = lambda?

    This probably has an easy solution, but I was wondering if anybody could help me solve and explain these two questions: (a) Show that the expectation of the random variable is E(X) = lambda (b) Show that the variance of the random variable is Var(X) = lambda Any help would be very...
  8. B

    poisson problem

    The number of cracks in a section of interstate highway that are significant enough to require repair is assumed to follow a Poisson distribution with a mean of two cracks per mile. What is the probability that there are no cracks that require repair in 5 miles of highway? any help guys? :)
  9. B

    probability question

    The number of cracks in a section of interstate highway that are significant enough to require repair is assumed to follow a Poisson distribution with a mean of two cracks per mile. What is the probability that there are no cracks that require repair in 5 miles of highway? any help guys? :yup:
  10. B

    how to compare poisson regression coefficients between two models in SPSS?

    I have two different Poisson models: Y = b1 + b2*X (1) Y = b1 + b3*X + b4*C (2) I would like to compare whether b2 is different than b3? The model is a poisson regression, is there a quick way to do it in SPSS? Many thanks Ezgi
  11. P

    Tricky Poisson Formula Rearrangement

    Hello, I am currently doing some bus stop designs. I have not done statistics for a while but remember once doing poisson distributions at Uni. The problem I have, I think, requires a specific arrangement of the poisson formula for cumulative distribution. If I have x number of buses...
  12. N

    Appropriate regression for dependent count data and independent "not count data"

    Hello, My independent data are continuous variables. My dependent variable is count data. I want to use regression to look for a relationship. Generally speaking, what is/are appropriate regression(s) for this situation? Thank you kindly, Mike
  13. S

    linear combination of exponential distributions

    I have an equation with linear combination of exponential distributions, i.e. sum (c_i * exp(a_i)) on the right hand side, and on the left hand side I have something that is best fitted by cauchy or log-normal... Now, I am looking for an estimating function for a linear combination of...
  14. R

    glm link function HELP! To gaussian, or not to gaussian, that is the question...

    Please ignore question no longer need help - thank you for all of your responses!
  15. T

    Poisson Distribution

    What is the probability there are at least 24 accidents at the intersection in a year if the mean number of accidents per month is 2.2? (answer=0.693) I keep getting 0.706, which is close to the listed answer, but I'm not sure if it is correct. My attempt: P(X≥24) = P(X>24)+P(X=24) =...