README.md

Dexter

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.

Installation

install.packages('dexter')

If you encounter a bug, please post a minimal reproducible example on github. We post news and examples on a website and blog.

Example

library(dexter)
# start a project and fill it with data
# verbAggrRules and verbAggrData are example datasets provided with dexter

db = start_new_project(verbAggrRules, "verbAggression.db")
add_booklet(db, verbAggrData, booklet_id = "verb_agg")

# Classical test theory
tia = tia_tables(db)

tia$booklets
booklet_id n_items alpha mean_pvalue mean_rit mean_rir max_booklet_score n_persons verb_agg 24 0.888 0.339 0.527 0.468 48 316
head(tia$items)

| booklet_id | item_id | mean_score| sd_score| max_score| pvalue| rit| rir| n_persons| |:------------|:------------|------------:|----------:|-----------:|-------:|------:|------:|-----------:| | verb_agg | S1DoCurse | 1.082| 0.807| 2| 0.541| 0.582| 0.519| 316| | verb_agg | S1DoScold | 0.832| 0.815| 2| 0.416| 0.651| 0.596| 316| | verb_agg | S1DoShout | 0.468| 0.709| 2| 0.234| 0.520| 0.460| 316| | verb_agg | S1WantCurse | 1.123| 0.827| 2| 0.562| 0.537| 0.468| 316| | verb_agg | S1WantScold | 0.930| 0.850| 2| 0.465| 0.593| 0.528| 316| | verb_agg | S1WantShout | 0.712| 0.777| 2| 0.356| 0.529| 0.464| 316|

# IRT, extended nominal response model
f = fit_enorm(db)

head(coef(f))

| item_id | item_score| beta| SE_beta| |:----------|------------:|-----------:|----------:| | S1DoCurse | 1| -1.3422140| 0.1541565| | S1DoCurse | 2| -0.6375015| 0.1418423| | S1DoScold | 1| -0.6702036| 0.1429057| | S1DoScold | 2| -0.2589855| 0.1579467| | S1DoShout | 1| 0.3254326| 0.1480166| | S1DoShout | 2| 0.3687574| 0.2099654|

# ability estimates per person
abl = ability(db, parms = f)
head(abl)

| booklet_id | person_id | booklet_score| theta| |:------------|:------------|---------------:|-----------:| | verb_agg | dx_0000001 | 13| -1.0238738| | verb_agg | dx_0000002 | 28| 0.3124831| | verb_agg | dx_0000003 | 4| -2.3748882| | verb_agg | dx_0000004 | 19| -0.4630604| | verb_agg | dx_0000005 | 7| -1.7721275| | verb_agg | dx_0000006 | 25| 0.0512826|

# ability estimates without item S1DoScold
abl2 = ability(db, parms = f, item_id != "S1DoScold")

# plausible values

pv = plausible_values(db, parms = f, nPV = 5)
head(pv)

| booklet_id | person_id | booklet_score| PV1| PV2| PV3| PV4| PV5| |:------------|:------------|---------------:|-----------:|-----------:|-----------:|-----------:|-----------:| | verb_agg | dx_0000001 | 13| -1.1129358| -0.3718473| -0.6251660| -1.0861430| -1.4627665| | verb_agg | dx_0000002 | 28| -0.0643628| 0.1312981| -0.6255087| -0.1063878| 0.3527158| | verb_agg | dx_0000003 | 4| -1.8603752| -2.5817701| -1.6376942| -1.7172643| -1.8129040| | verb_agg | dx_0000004 | 19| -1.0663677| -0.6810231| -1.1512542| -0.9481833| -0.8004328| | verb_agg | dx_0000005 | 7| -2.0083386| -1.5279208| -1.3307093| -1.5430697| -1.3224421| | verb_agg | dx_0000006 | 25| 0.2020330| 0.2050144| 0.2221347| -0.4249511| 0.0809038|



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dexter documentation built on Oct. 28, 2021, 5:08 p.m.