# bayes

1. ### 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...
2. ### Approximate Bayesian Computation and joint posteriors

Hi! I am performing Approximate Bayesian Computation (ABC) in phylogenetic research. I have a few questions for which I am looking for a useful answer (as I am a biologist, but not a statistician). (1) How can I combine the posterior distributions of several ABC runs? I need to calculate...
3. ### How does the Bayesian equation accomodate new info to provide a better decision?

An example from the literature. A taxi causes an accident and then leaves the scene. A witness identifies the taxi as Blue. It is estimated that the probability of correct ID is 80%. 15% of the taxis are Blue, 85% are Green. This gives a 41% chance that the taxi is Blue. My question is, what...
4. ### Bayesian: Defining priors from *same* data set you're modeling

I believe that it is inappropriate to define prior distributions based on the same data you will be analyzing with those priors. In other words, the priors should not come from the **same** data set (i.e., from descriptive stats, etc) that you are about to estimate a model for. Does anyone...
5. ### really urgent probability problem - is it bayesian?

Hi, I have an urgent problem but I'm a little lost. Is this probability question referring to the use of Bayes' theorem? Firstly, I don't exactly understand what is meant by what is "the probability of the sample text". Does this mean we need to find P(I . O)? This is as far as I can...