```
# The first example fits the MPT model presented in Riefer and Batchelder (1988, Figure 1)
# to the data presented in Riefer and Batchelder (1988, Table 1)
# Note that Riefer and Batchelder (1988, pp. 328) did some hypotheses tests not replicated here.
# Instead, we use each condition (i.e., row in Table 1) as a different dataset.
# load the data
data(rb.fig1.data, package = "MPTinR")
#get the character string with the position of the model:
model1 <- system.file("extdata", "rb.fig1.model", package = "MPTinR")
model1.eqn <- system.file("extdata", "rb.fig1.model.eqn", package = "MPTinR")
# just fit the first dataset:
fit.mpt(rb.fig1.data[1,], model1, n.optim = 1)
fit.model(rb.fig1.data[1,], model1, n.optim = 1)
#fit all datasets:
fit.mpt(rb.fig1.data, model1, n.optim = 1)
fit.model(rb.fig1.data, model1, n.optim = 1)
#fit all datasets using the .EQN model file:
fit.mpt(rb.fig1.data, model1.eqn, n.optim = 1)
#fit using a textConnection (i.e., you can specify the model in your script/code):
model1.txt <- "p * q * r
p * q * (1-r)
p * (1-q) * r
p * (1-q) * (1-r) + (1-p)"
fit.mpt(rb.fig1.data, textConnection(model1.txt), n.optim = 1)
# The second example fits the MPT model presented in Riefer and Batchelder (1988, Figure 2)
# to the data presented in Riefer and Batchelder (1988, Table 3)
# First, the model without restrictions is fitted: ref.model
# Next, the model with all r set equal is fitted: r.equal
# Then, the model with all c set equal is fitted: c.equal
# Finally, the inferential tests reported by Riefer & Batchelder, (1988, p. 332) are executed.
# get the data
data(rb.fig2.data, package = "MPTinR")
# positions of model and restriction files:
model2 <- system.file("extdata", "rb.fig2.model", package = "MPTinR")
model2r.r.eq <- system.file("extdata", "rb.fig2.r.equal", package = "MPTinR")
model2r.c.eq <- system.file("extdata", "rb.fig2.c.equal", package = "MPTinR")
# The full (i.e., unconstrained) model
(ref.model <- fit.mpt(rb.fig2.data, model2))
# All r equal
(r.equal <- fit.mpt(rb.fig2.data, model2, model2r.r.eq))
# All c equal
(c.equal <- fit.mpt(rb.fig2.data, model2, model2r.c.eq))
# is setting all r equal a good idea?
(g.sq.r.equal <- r.equal[["goodness.of.fit"]][["G.Squared"]] -
ref.model[["goodness.of.fit"]][["G.Squared"]])
(df.r.equal <- r.equal[["goodness.of.fit"]][["df"]] -
ref.model[["goodness.of.fit"]][["df"]])
(p.value.r.equal <- pchisq(g.sq.r.equal, df.r.equal , lower.tail = FALSE))
# is setting all c equal a good idea?
(g.sq.c.equal <- c.equal[["goodness.of.fit"]][["G.Squared"]] -
ref.model[["goodness.of.fit"]][["G.Squared"]])
(df.c.equal <- c.equal[["goodness.of.fit"]][["df"]] -
ref.model[["goodness.of.fit"]][["df"]])
(p.value.c.equal <- pchisq(g.sq.c.equal, df.c.equal , lower.tail = FALSE))
# You can specify restrictions also via a list instead of an external file:
# All r equal
r.equal.2 <- fit.mpt(rb.fig2.data, model2, list("r0 = r1 = r2= r3 = r4"), n.optim = 5)
all.equal(r.equal, r.equal.2)
# All c equal
c.equal.2 <- fit.mpt(rb.fig2.data, model2, list("c0 = c1 = c2 = c3= c4"))
all.equal(c.equal, c.equal.2)
if (FALSE) {
# Example from Broder & Schutz (2009)
# We fit the data from the 40 individuals from their Experiment 3
# We fit three different models:
# 1. Their 2HTM model: br.2htm
# 2. A restricted 2HTM model with Dn = Do: br.2htm.res
# 3. A 1HTM model (i.e., Dn = 0): br.1htm
# We fit the models with, as well as without, applied inequality restrictions (see Details)
# that is, for some models (.ineq) we impose: G1 < G2 < G3 < G4 < G5
# As will be apparent, the inequality restrictions do not hold for all individuals.
# Finally, we compute the FIA for all models, taking inequalities into account.
data(d.broeder, package = "MPTinR")
m.2htm <- system.file("extdata", "5points.2htm.model", package = "MPTinR")
r.2htm <- system.file("extdata", "broeder.2htm.restr", package = "MPTinR")
r.1htm <- system.file("extdata", "broeder.1htm.restr", package = "MPTinR")
i.2htm <- system.file("extdata", "broeder.2htm.ineq", package = "MPTinR")
ir.2htm <- system.file("extdata", "broeder.2htm.restr.ineq", package = "MPTinR")
ir.1htm <- system.file("extdata", "broeder.1htm.restr.ineq", package = "MPTinR")
# fit the original 2HTM
br.2htm <- fit.mpt(d.broeder, m.2htm)
br.2htm.ineq <- fit.mpt(d.broeder, m.2htm, i.2htm)
# do the inequalities hold for all participants?
br.2htm.ineq[["parameters"]][["individual"]][,"estimates",]
br.2htm[["parameters"]][["individual"]][,"estimates",]
# See the difference between forced and non-forced inequality restrictions:
round(br.2htm[["parameters"]][["individual"]][,"estimates",] -
br.2htm.ineq[["parameters"]][["individual"]][,"estimates",],2)
# The same for the other two models
# The restricted 2HTM
br.2htm.res <- fit.mpt(d.broeder, m.2htm, r.2htm)
br.2htm.res.ineq <- fit.mpt(d.broeder, m.2htm, ir.2htm)
round(br.2htm.res[["parameters"]][["individual"]][,"estimates",] -
br.2htm.res.ineq[["parameters"]][["individual"]][,"estimates",],2)
# The 1HTM
br.1htm <- fit.mpt(d.broeder, m.2htm, r.1htm)
br.1htm.ineq <- fit.mpt(d.broeder, m.2htm, ir.1htm)
round(br.2htm.res[["parameters"]][["individual"]][,"estimates",] -
br.2htm.res.ineq[["parameters"]][["individual"]][,"estimates",],2)
# identical to the last fit of the 1HTM (using a list as restriction):
br.1htm.ineq.list <- fit.mpt(d.broeder, m.2htm, list("G1 < G2 < G3 < G4 < G5", "Dn = 0"))
all.equal(br.1htm.ineq, br.1htm.ineq.list) # TRUE
# These results show that inequality restrictions do not hold for all datasets.
# (It would look differently if we excluded critical cases,
# i.e., 2, 6, 7, 10, 18, 21, 25, 29, 32, 34, 35, 37, 38)
# Therefore, we get the FIA for the models as computed above
br.2htm.fia <- fit.mpt(d.broeder, m.2htm, fia = 200000)
br.2htm.ineq.fia <- fit.mpt(d.broeder, m.2htm, i.2htm, fia = 200000)
br.2htm.res.fia <- fit.mpt(d.broeder, m.2htm, r.2htm, fia = 200000 )
br.2htm.res.ineq.fia <- fit.mpt(d.broeder, m.2htm, ir.2htm, fia = 200000)
br.1htm.fia <- fit.mpt(d.broeder, m.2htm, r.1htm, fia = 200000)
br.1htm.ineq.fia <- fit.mpt(d.broeder, m.2htm, ir.1htm, fia = 200000)
# Model selection using the FIA
(br.select <- select.mpt(list(br.2htm.fia, br.2htm.ineq.fia, br.2htm.res.fia,
br.2htm.res.ineq.fia, br.1htm.fia, br.1htm.ineq.fia)))
# The same results, ordered by FIA
br.select[order(br.select[,"delta.FIA.sum"]),]
# Note that FIA for individual data (.sum) is not consistent (i.e., the penalty
# for the nested model br.1htm.ineq.fia is not really smaller than the penalty
# for the superordinate model br.2htm.ineq.fia).
# Hence, one should use the aggregated data for this analysis (not shown here)!
# Compare this with the model selection not using FIA:
select.mpt(list(br.2htm, br.2htm.ineq, br.2htm.res, br.2htm.res.ineq, br.1htm, br.1htm.ineq))
# Only use the aggregated data:
d.broeder.agg <- colSums(d.broeder)
br.2htm.agg <- fit.mpt(d.broeder.agg, m.2htm)
br.2htm.res.agg <- fit.mpt(d.broeder.agg, m.2htm, r.2htm)
br.1htm.agg <- fit.mpt(d.broeder.agg, m.2htm, r.1htm)
select.mpt(list(br.2htm.agg, br.2htm.res.agg, br.1htm.agg), output = "full")
# compare speed of no multicore versus multicore for multiple datasets:
require(snowfall)
# change number of CPUs if more are available
nCPU = 2
sfInit( parallel=TRUE, cpus=nCPU, type = "SOCK" )
# NO multicore
system.time(fit.mpt(d.broeder, m.2htm))
# multicore:
system.time(fit.mpt(d.broeder, m.2htm, multicore = "individual"))
sfStop()
}
```

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