irt 0.2.8

• Added kappa_coef() function to calculate Cohen’s weighted/unweighted Kappa coefficient.
• Response objects prints ‘misc’ fields without an error when there is a factor type variable.
• Fixed an error in the function irt:::marginal_reliability(..., method = "empirical").

irt 0.2.6

• Plot functions can now suppress plot titles by setting title = NULL.
• item_analysis() function now has a new argument stats where only selected item analysis statistics can be calculated.
• item_analysis() function can now calculate pval_unadj which is simply the mean of item scores. pval is still the mean of item scores divided by each item’s maximum possible score.
• Added area_between_icc() function to calculate the area between two item characteristic curves of two unidimensional dichotomous items. The function can calculate either exact area (except when 3PL with different pseudo-guessing parameters) or area between two theta values.
• cat_sim() function can use MAP (maximum-a-posteriori or Bayes Modal) and MAP + ML (i.e. MAP until an imperfect response string and ML after) ability estimation methods.
• Responses, items administered, administered item IDs, estimates before or after the administration of an item can be extracted from the individual CAT output. For details, see “?$.cat_output”.
• Added output_type argument to est_ability(, output_type = ) function with available following output types: "list", "data.frame", "tibble". Previously, the output was only a “list”.

irt 0.1.4

• Bug fix: An Itempool object with one testlet can be printed without an error.
• Added $item_ids to testlet object to get the ids of the items within the testlet.
• Fixed bugs in plot_empirical_icc() function.

irt 0.1.3

• Added $max_score for Testlet objects. For a given Testlet object t1, t1$max_score returns the maximum obtainable score by all items within the testlet.
• Added $resp_item_list for Itempool objects. For an Itempool object ip, ip$resp_item_list will combine items that are not in a testlet and items within a testlet and returns a list object that is composed of only Item objects.

irt 0.1.2

• Package can be used in MacOS as well. Resolved compiler related issues.
• Added est_bilog() function to estimate item parameters for “1PL”, “2PL” and “3PL” models using BILOG-MG on computers with Windows OS. This function requires an installed BILOG-MG program on the machine.

irt 0.1.0

• This is the initial release of the package.