Prior definitions for measr models — measrprior • measr

Create prior definitions for classes of parameters, or specific parameters.

Usage

measrprior(
  prior,
  class = c("structural", "intercept", "maineffect", "interaction", "slip", "guess"),
  coef = NA,
  lb = NA,
  ub = NA
)

prior(prior, ...)

prior_(prior, ...)

prior_string(prior, ...)

Arguments

prior: A character string defining a distribution in Stan language. A list of all distributions supported by Stan can be found in Stan Language Functions Reference at https://mc-stan.org/users/documentation/.
class: The parameter class. Defaults to "intercept". Must be one of "intercept", "maineffect", "interaction" for the LCDM, or one of "slip" or "guess" for DINA or DINO models.
coef: Name of a specific parameter within the defined class. If not defined, the prior is applied to all parameters within the class.
lb: Lower bound for parameter restriction. Defaults to no restriction.
ub: Upper bound for parameter restriction. Defaults to no restriction.
...: Additional arguments passed to measrprior().

Value

A tibble of class measrprior.

Functions

prior(): Alias of measrprior() which allows arguments to be specified as expressions without quotation marks.
prior_(): Alias of measrprior() which allows arguments to be specified as one-sided formulas or wrapped in base::quote().
prior_string(): Alias of measrprior() which allows arguments to be specified as character strings.

Examples

# Use alias functions to define priors without quotes, as formulas,
# or as character strings.
(prior1 <- prior(lognormal(0, 1), class = maineffect))
#> # A tibble: 1 × 3
#>   class      coef  prior_def      
#>   <chr>      <chr> <chr>          
#> 1 maineffect NA    lognormal(0, 1)

(prior2 <- prior_(~lognormal(0, 1), class = ~maineffect))
#> # A tibble: 1 × 3
#>   class      coef  prior_def      
#>   <chr>      <chr> <chr>          
#> 1 maineffect NA    lognormal(0, 1)

(prior3 <- prior_string("lognormal(0, 1)", class = "maineffect"))
#> # A tibble: 1 × 3
#>   class      coef  prior_def      
#>   <chr>      <chr> <chr>          
#> 1 maineffect NA    lognormal(0, 1)

identical(prior1, prior2)
#> [1] TRUE
identical(prior1, prior3)
#> [1] TRUE
identical(prior2, prior3)
#> [1] TRUE

# Define a prior for an entire class of parameters
prior(beta(5, 25), class = "slip")
#> # A tibble: 1 × 3
#>   class coef  prior_def  
#>   <chr> <chr> <chr>      
#> 1 slip  NA    beta(5, 25)

# Or for a specific item (e.g., just the slipping parameter for item 7)
prior(beta(5, 25), class = "slip", coef = "slip[7]")
#> # A tibble: 1 × 3
#>   class coef    prior_def  
#>   <chr> <chr>   <chr>      
#> 1 slip  slip[7] beta(5, 25)