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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 blog, it's also the place for general questions.

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$testStats
booklet_id nItems alpha meanP meanRit meanRir maxTestScore N
verb_agg 24 0.888 0.339 0.527 0.468 48 316
head(tia$itemStats)
booklet_id item_id meanScore sdScore maxScore pvalue rit rir n
verb_agg S1DoCurse 1.082 0.808 2 0.541 0.582 0.519 316
verb_agg S1DoScold 0.832 0.817 2 0.416 0.651 0.596 316
verb_agg S1DoShout 0.468 0.710 2 0.234 0.520 0.460 316
verb_agg S1WantCurse 1.123 0.828 2 0.562 0.537 0.468 316
verb_agg S1WantScold 0.930 0.852 2 0.465 0.593 0.528 316
verb_agg S1WantShout 0.712 0.778 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_b
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 sumScore theta
verb_agg dxP1 13 -1.0218323
verb_agg dxP10 9 -1.4832759
verb_agg dxP100 14 -0.9204799
verb_agg dxP101 0 -Inf
verb_agg dxP102 12 -1.1276084
verb_agg dxP103 8 -1.6191967
# 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 sumScore PV1 PV2 PV3 PV4 PV5
verb_agg dxP1 13 -0.8830828 -0.7066814 -0.7703465 -1.0441590 -0.8918823
verb_agg dxP10 9 -1.5388849 -1.0014150 -1.7249607 -1.3372498 -1.5627987
verb_agg dxP100 14 -0.6678893 -1.4039775 -0.6161149 -0.9249503 -0.7607182
verb_agg dxP101 0 -2.3034185 -3.0623911 -2.3793639 -3.1658178 -3.3999772
verb_agg dxP102 12 -1.0434515 -1.5317991 -1.1518701 -1.0103475 -1.0057779
verb_agg dxP103 8 -2.0467553 -1.5357100 -2.0598186 -1.2366479 -1.7367032

Contributing

Contributions are welcome but please check with us first about what you would like to contribute.

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