bayes

  1. Lazar

    Repeated Measures RCT mediation help

    I have a repeated measures dataset with baseline and 12 and 24 month follow-up. I need to fit a mediation model to this data. I am unsure whether my approach (see below) makes sense. The questions I have are: 1. If the model has Poisson link function for the outcome is the traditional a*b...
  2. J

    Baysian statistical test

    Hi, how can we perform a baysian test which is alternative of Wilcox test.? My data is not normalized so can't do baysian t tests.
  3. D

    Demonstrating that MAP -> MLE, Bayes

    Note - I can't work out how to write in LaTeX on here, and ascii maths can be quite painful, as a result I have included the LaTeX in this post and provided links where the LaTeX can be read rendered. Also, any answers that make use of R software are fine, I don't have access to anything such...
  4. R

    Bayes - need help informing priors

    Hi! Anyone here familiar with Bayesian inference? I would like to inform priors for an analysis. I have Odds Ratios and 95% CIs. How would I calculate the variance from the CIs. I know how to calculate SEs, but I don't think that is the custom for priors (its usually mean and variance)...
  5. G

    Bayes Hypothesis testing via model comparison

    Any idea for this exercise? Thanks for help...
  6. I

    Urgent: Probability of having Lyme Disease and Bayes theorem

    I recently found a deer tick on me (had been there for several days). I have no symptoms. My Dr. says I could ignore it or take a course of antibiotics. Given that the probability that this tick carried lyme is 35% and given that the probability of having Lyme in the absence of symptoms is 50%...
  7. A

    bayes for generating new data

    I am estimating a tree inventory for a city. I have already measured the heights and identified the species for about 1000 trees in some areas of the city and I want to estimate the remaining species composition based on the collected data. There are about 150 different species. I have...
  8. R

    Bayesian exercise

    -2 down vote favorite I cant get my head round the following exercise: You are testing dice for a casino to make sure that sixes do not come up more frequently than expected. Because you do not want to manually roll dice all day, you design a machine to roll a die repeatedly and record the...
  9. B

    bayesian statistics

    I have a large amount of data, given totals for every hour over a year period for the following columns: # of Jams Jam event time in minutes # of Full occurances Full event time in minutes and Runtime, product flow (counts) I am trying to create a bayesian model using iPython and...
  10. J

    Bayesian statistics proof question

    I know that if the prior distribution is chosen to be a continuous uniform distribution, then the exact posterior distribution will simply the normalized version of the likelihood function. I was wondering how i would write this out as a proof?
  11. Lazar

    Cross-classification BUGS

    Hi All, I have a hierarchical Bayes model that looks like: model{ #Overaching model for (i in 1:n){ y[i] ~ dnorm (yHat[i], tau.y) yHat[i] <- a[id[i]] + b.group*group[i] + b.wave*wave[i] + b.int*wave[i]*group[i] } #Fixed Effects b.group ~ dnorm(0, .0001) b.wave ~...
  12. T

    Multi-level Bayes

    I guess that this is a multi level Bayes problem but there maybe a better technical name for it that I am not aware. Three jars contain tokens of two different colors; red and green. Jar A has 40% red and 60% green. Jar B has 80% red and 20% green. Jar C has 30% red and 70% green. Two...
  13. rogojel

    Bayes statistics - sensitivity to priors

    Hi, I came across a statement in a review of a research field, where they were determining an unknown parameter using Bayesian statistics. The reviewer said that using Bayes statistics to estimate the parameter is uncontroversial, but many of the papers dealing with this estimation are weak...
  14. G

    Problem in Bayes' Theorem/ Conditional Probability

    Hi everyone ! I'm new to this site and this is my first post. This is a problem I found in my Stats textbook under the Bayes Theorem section. Here's the problem: Three urns of the same appearance have the following proportion of balls. First urn: 2 Black 1 White Second urn:1 Black 2...
  15. S

    Help with the Beta Distribtuion

    Background: I'm currently trying to learn how to use Bayesian Analysis for split testing two sets of binomial data. (Web analytics, Multi-Armed Bandit approach, etc). The Beta distribution kept coming up in this research, so Im trying to understand and apply it better. So, the best...
  16. Lazar

    Bayes CFA

    Hi Folks, I have several questions about Bayes CFA in Open bugs that I hope you might be able to help me out with. First the setup: Here is a basic two factor CFA set up for the HS data that is available in several R packages ###Bugs CFA model 2 factors. All cross loadings zero###...
  17. Dason

    [Interview] SPUNKY IN YOUR FACE

    It's been a while since we've had an interview thread! Spunky graciously accepted the request to do an interview. Spunky has been a member since January of 2011. Spunky was recently on a TS hiatus (very dark times for TS) but has had a glorious return! Typically we give about a week for each...
  18. trinker

    Bayesian vs. Frequentist for the applied researcher

    There's been a lot of talk about Bayes lately in my life, talkstats, class, articles etc. I feel like it's becoming something researchers can't hide from anymore. My question is this: We generally teach applied researchers (ie a content person who learns statistical methods) frequentist...
  19. R

    Bayes, and the Horse He Rode In On

    A professor presented this question: "If a cancer screen comes back positive in 68 of 75 cases of actual cancer and in 5 of 191 cases of no cancer, when the actual cancer rate in the total sample is 1/3, what is the probability of a false negative test result (patient has cancer but test comes...
  20. B

    A probability question

    I am trying to revise for a test, and am working through some prep questions. I am struggling on this one, could anyone help? Suppose there is a medical diagnostic test for a disease. The sensitivity of the test is .95. This means that if a person has the disease, the probability that the...