Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [brms]

brms is an R package interfacing stan for Bayesian analysis

28 questions
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Can I Use the loo function to help me choose between a Poisson and Bernouilli distribution in bayesian

I have two models exactly similar, but I’m using a Poisson distribution for one and a Bernoulli distribution for the other. Can I trust the information coming out of loo to help me choose? The Bernoulli model comes on top. rbpa <- brm(status ~ ... ,…
mountaingoat19
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Difference in fitting to right censored data between MLE and Bayesian method

I am fitting a Weibull curve to right censored data. I am doing it by general MLE method using Survival::survreg() as well as Bayesian method using brms::brm. I am pretty sure that I am getting the model right. In the results, I am getting similar…
PitPartizan
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Default Priors for Intercept and Standard Deviations in R package brms

The only resource I found explaining the default priors in brms is its manual (newest version, updated 03/14/2021) for function set_prior(). For the intercept, the manual does not specify how the default prior is selected. When I fit a generalized…
Cece
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Plot predict probabilities wiht ggplot2 and brms

I'm a PhD student in psycholinguistics and I'm having trouble in modeling some ordinal data. I have an ordinal response (completely disagree, disagree, neutral, agree, completely agree) and two categorical predictors (order: um-todo x todo-um;…
Igor de Oliveira Costa
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Method for Predicting Longitudinal Diagnostic Switching and Instability

Context Within my field (neuropsychology), there is a well-known issue for some individuals to have very unstable diagnoses overtime. My area of interest is in dementia where the ideal diagnostic progression is from normal condition to mild…
Billy
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Interaction between two factors as Random effects in mixed model in R

I would like to know how to write random effects of two interacting factors. For example, I have 6 species which were planted in 48 plots and replicated in two blocks. There are in total 48 combinations (all possible 1, 2, 3, 5, and 6 species…
Tanvir Shovon
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How to interpret the evidence ratio using BRMS in R?

I am running a frequentist multi-level meta-analysis. However a reviewer has requested a bayesian alternative, so I can provide Bayes Factors. My summary of my code is as follows: priors <- c(prior(normal(0, 1), class = Intercept), …
Ajj1988
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Bayesian GLM where the response variable is count classes

Description of data I have to analyze some data where the response variable is the counts of number of insects observed feeding on a bait at many time points. The treatments are three different types of bait and there are several replicates per…
qdread
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fitting multilevel models for data that is both multiple membership and repeated measures

I have a longitudinal dataset with 5 repeated measures, where individuals are nested within counties and may have moved to a new county during the study period, e.g., > df # A tibble: 15 × 4 ID wave county Y 1…
epigurl
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Help in understanding zero inflated neg binomial model summary

I'm writing this topic because I would need to get some more information about model conversion in brms (zero-inflated_negbinomial) model. Let's say I have this model result : Where I want to model how many fish are being caught by fishermen at a…
chippycentra
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Interpreting non linear brms output - estimates of posterior cooefficient and user supplied formula

I am a bit confused about how to approximate the equation from a nonlinear model constructed in brms, and was hoping someone could explain it to me. Say I have the below model: Family: lognormal Links: mu = identity; sigma = identity Formula:…
Kai P
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Differing posterior predictive checks for logistic binomial model with and without addition-terms

[apologies for cross posting] I’m fitting a logistic binomial model where the response variable is the sum of how many times a target picture was looked at during a certain time period out of how many times all pictures were looked at during that…
kathi
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binomial mixed model random effects structure

I am having difficulty with the structure of a binomial mixed effects model. I'm using brms, but my question is more about model design than bayesian modeling so I hope to get some good insights from the broader audience here. Briefly, I have a list…
rstewa03
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How do I get around this "Argument 'coef' may not be specified when using boundaries."

I have a model, the brms code is given below. It is a system of equations (I am estimating demand for two categories of goods). Economic theory tells me that the intercepts have to be restricted to the unit interval. So, I have set my prior, lb, and…
Loren P Wagner
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Hierachical Bayesian modelling using brms: how to insert a prior that reflects cut-offs of Reaction Times distribution?

I am running a hierarchical Bayesian model using brms on reaction times (RTs) of a GoNogo task. The predictors are categorical and include the 3 stimuli/condition that participants observed and the 2 sequences of trials. I used an ex-Gaussian…
TomC
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