getTheta function

Obtain theta estimates

getTheta is a helper function for obtaining theta estimates. Estimates are obtained using an expected a posteriori (EAP) method.

getTheta(
  data,
  ipar,
  scale = "combined",
  model = "grm",
  theta_grid = seq(-4, 4, 0.1),
  prior_dist = "normal",
  prior_mean = 0,
  prior_sd = 1
)

Arguments

• data: a PROsetta_data object.
• ipar: a data.frame containing item parameters.
• scale: the index of the scale to use. combined refers to the combined scale. (default = combined)
• model: the item model to use. Accepts grm or gpcm. (default = grm)
• theta_grid: the theta grid to use for numerical integration. (default = seq(-4, 4, .1))
• prior_dist: the type of prior distribution. Accepts normal or logistic. (default = normal)
• prior_mean: mean of the prior distribution. (default = 0.0)
• prior_sd: SD of the prior distribution. (default = 1.0)

Returns

getTheta returns a list containing EAP estimates.

Examples

x <- runLinking(data_asq, method = "FIXEDPAR")

o <- getTheta(data_asq, x$ipar_linked, scale = 1)
o$theta
o$item_idx

o <- getTheta(data_asq, x$ipar_linked, scale = 2)
o$theta
o$item_idx

o <- getTheta(data_asq, x$ipar_linked, scale = "combined")
o$theta
o$item_idx