Specify a Student-t prior — prior_student

Heavier-tailed alternative to prior_normal(). For logistic-regression coefficients with unit-scale predictors, the Stan community prior-choice recommendations suggest Student-t with df between 3 and 7 as a robust weakly informative prior (Gelman et al., 2008).

Usage

prior_student_t(df = 5, mean = 0, sd = 2.5, autoscale = FALSE)

Arguments

df: Degrees of freedom (must be positive). Values in 3:7 are recommended for logistic-regression coefficients.
mean: Prior location (default 0).
sd: Prior scale (default 2.5).
autoscale: See prior_normal(). Default FALSE.

Value

A list with components distribution = "student_t", df, mean, sd, autoscale.

Examples

# Gelman et al. 2008 recommendation for logistic-regression coefficients
prior_student_t(df = 5, mean = 0, sd = 2.5)
#> $distribution
#> [1] "student_t"
#> 
#> $mean
#> [1] 0
#> 
#> $sd
#> [1] 2.5
#> 
#> $df
#> [1] 5
#> 
#> $autoscale
#> [1] FALSE
#>