What should I know about the Jags model?

What should I know about the Jags model?

This tutorial will work through the code needed to run a simple JAGS model, where the mean and variance are estimated using JAGS. The model is likely not very useful, but the objective is to show the preperation and coding that goes into a JAGS model.

What should I bundle my data into for Jags?

We need to bundle our data into a list that JAGS will be able to read. This is very simple in this exercise and generally very simple in more complex models. Just make sure you have all the elements in that the model needs, which may extend beyond data.

Which is the best way to plot Jags output?

There are a number of packages that can also be used to plot JAGS output and make things simpler. However, it is not a bad idea to become comfortable with the JAGS model object as there may come a model that has sufficiently complex output that a canned diagnostic does not work. Gelman, Andrew, and Jennifer Hill. 2006.

How is Jags not a procedural language like R?

JAGS does the rest… JAGS is not a procedural language like R; you can write the model code in any order Define model in BUGS language (write in R and export as text file to be read by JAGS) Define parameters to keep track of (i.e., parameters of interest)

How to generate random starting values in Jags?

Just make sure you have all the elements in that the model needs, which may extend beyond data. Using an equals sign (not assignment operator), set the data that JAGS is looking for on the left side, to the input data on the right side. JAGS will generate random starting values if not specified, and for simple models this should work.

Can a Jags command never need to be modified?

This simple code adjusts the settings, and the JAGS command will never need to be modified. JAGS models can get complex and often have many (hundreds or thousands) of parameters. Here we will specify that we want to monitor both parameters in this model, but in the future, you may want to specify only some parameters of interest.

What should a value near 1 be in Jags?

Values near 1 indicates likely convergence, a value of ≤ 1.1 ≤ 1.1 is considered acceptable by some This tutorial will work through the code needed to run a simple JAGS model, where the mean and variance are estimated using JAGS.