getTheta: Obtain theta estimates

In PROsetta: Linking Patient-Reported Outcomes Measures

Obtain theta estimates

Description

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

Usage

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)

Value

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

PROsetta documentation built on Feb. 16, 2023, 9:14 p.m.