A system for the management, assessment, and psychometric analysis of data from educational and psychological tests. Developed at Cito, The Netherlands, with subsidy from the Dutch Ministry of Education, Culture, and Science.
Dexter is an R package for psychometric analysis of data from educational and psychological tests. Dexter typically works with project database files saved on disk.
library(dexter)# verbAggrRules and verbAggrData are example datasets provided with dexterdb = start_new_project(verbAggrRules, "verbAggression.db")add_booklet(db, verbAggrData, booklet_id = "verb_agg")# Classical test theorytia = tia_tables(db)tia$testStats
# IRT, extended nominal response modelf = fit_enorm(db)head(coef(f))
# ability estimates per personabl = ability(db, parms = f)head(abl)
# ability estimates without item S1DoScoldabl2 = ability(db, parms = f, item_id != "S1DoScold")# plausible valuespv = plausible_values(db, parms = f, nPV = 5)head(pv)
Contributions are welcome but please check with us first about what you would like to contribute.
expected_score() for tests and items in the ENORM.
change in the algorithm for MLE estimation method in ability and ability_tables. The new algorithm is more precise so small changes in (the lower digits of) computed theta values may occur with respect to previous versions of dexter.
corrected a bug in the reporting of standard errors for Bayesian estimation of the ENORM. The SE's reported in previous versions of dexter were too high.
corrected bug in plot for DIF (item labels were reversed) introduced in 0.8.0
significant speed increases in plausible_values, plausible_scores, ability and ability_tables
added plot method for the extended nominal response model
add_response_data() for importing normalized data
profile_tables() functions added for analysis of individual deviation profiles
(misfit) compared to the fitted model.
bugfix for solaris
You may want to take a look at the new sister package, dextergui
support for RSQLite release 2.1.0+ which broke dexter 0.6.0.
probability_to_pass() function added for equating to a reference test that is
connected to a target test.
ability_tables() function added to generate score transformation tables
for arbitrary subsets of items.
ability_tables() can now also
take Jeffreys prior and variatons of the normal prior and can optionally
output standard errors.
plausible_scores() function added to generate scores on arbitrary itemsets
(or the entire bank).
Updates to documentation.
plausible_values() can now work with covariates.
fit_enorm() can optionally take fixed_parameters into account.
Significant speed increases in profile_plot, iTIA and iModels and minor speed increases in other functions.
Further includes more user control over plotting parameters, updates to documentation, several bugfixes and some smaller updates.
We go straight from version 0.1.7 to version 0.4.2 in a major new release. The functionality envisaged for two other related packages, enorm and roger, has now been all incorporated into dexter.
The database has been completely rewritten. Databases created with 0.1.7 can be imported but are no longer maintained.
Many functions now support flexible subsetting of data through a predicate expression; furthermore, the data source can be either the dexter database (more usual), or a data frame or tibble. The latter can be useful in simple simulations or in some non-standard situations.
Basic test and item analysis has been extended with two interactive tools based on shiny, and with an exploratory tool to search for DIF.
Version 0.4.2 estimates the Extended NOminal Response Model (ENORM) by either CML or a Gibbs sampler, computes person scores by either MLE, EAP, or plausible values, and provides a new test for the hypothesis of no true individual differences. In addition, it supports a method for standard settings known as 3DC.
Several vignettes have been added to explain the new features in detail.