R/estimates.R

In UO-BRT/exirt: Analyze data from the Oregon Extended Assessment

#' High-level function to estimate/create student estimates
#'
#' This function does the modeling and pulls the student estimates
#' for every grade/content area (unless a specific grade/content area is
#' supplied). Student estimates are computed with all field-test
#' items removed.
#'
#' @inheritParams rasch
#' @inheritParams get_person_estimates
#' @export

estimate_abilities <- function(test, single_df = TRUE) {
  models <- rasch(test)
  pers <- get_person_estimates(models, test, single_df)
  nms <- names(pers)
  pers$content <- gsub("^(.+)_G.+$", "\\1", pers$test)
  pers$grade <- gsub("^.+_G(\\d\\d?)$", "\\1", pers$test)
  pers[c("content", "grade", nms)]
}

#' High-level function to estimate/create item difficulty estimates
#' for field-test items
#'
#' This function does the modeling and pulls the item difficulty estimates
#' for every grade/content area (unless a specific grade/content area is
#' supplied). Operational items are anchored at their previously estimated
#' item difficulty values.
#'
#' @inheritParams rasch
#' @inheritParams get_item_diffs
#' @export

estimate_ft_difficulties <- function(test, single_df = TRUE) {
  models <- rasch(test, omit_field_test = FALSE)
  ft_items <- get_ft_items(models)

  # consider changing to an error
  if (nrow(ft_items) == 0) {
    warning("No field test items detected.", call. = FALSE)
    return()
  }

  item_estimates <- get_item_diffs(models, single_df)

  # This only works for a list of tests (all of them), not just a single test
  # because you need to only merge on `"item_id"` if it's a single test
  out <- merge(
    item_estimates,
    ft_items,
    by = c("test", "item_id"),
    all.y = TRUE
  )

  # same as above
  out <- out[order(out$test, out$item_loc), ]
  out <- out[, -grep("item_loc", names(out))]

  if (!single_df) {
    out <- split(out, out$test)
    out <- lapply(out, function(x) {
      rownames(x) <- NULL
      x
    })
  }
  out
}