# 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 ub to reflect that. However, I get the error "Error: Argument 'coef' may not be specified when using boundaries." I take this to mean that I have to restrict all my population effects (slope and intercept) to the unit interval or none of them to the unit interval. Is this the case? Is there a way around this?

formula <- mvbf(Foodaway ~ 0 +
Intercept +
log(CPI_FA) +
log(CPI_FH) +
log(CPI_Other) +
I(log(TE)-LogP),
Foodhome ~ 0 +
Intercept +
log(CPI_FA) +
log(CPI_FH) +
log(CPI_Other) +
I(log(TE)-LogP),
rescor = TRUE)

fit <- brm(formula,
data = fitdata2017_expanded,
prior = c(set_prior("beta(1, 1)", class = "b", coef = "Intercept",
resp = "Foodaway", lb = 0, ub = 1),
set_prior("beta(1, 1)", class = "b", coef = "Intercept",
resp = "Foodhome", lb = 0, ub = 1),
prior("normal(0,5)", class = "b", resp = "Foodaway"),
prior("normal(0,5)", class = "b", resp = "Foodhome")),
cores = 4,
chains = 4,
iter = 5000,
control = list(max_treedepth = 15))$$$$
`
• I don't know what does that mean, but if you set a Beta prior you don't need to specify the bounds 0 and 1, since a Beta random variable lies between 0 and 1. – Stéphane Laurent May 15 at 15:11