Generate IRT Object

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Description

Create an IRT object with generated values

Usage

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gen.irt(n.peo, n.item, thetas = NULL, a = NULL, b = NULL, c = NULL,
  theta.mu = 0, theta.sig = 1, a.mu = 0, a.sig = 0.15, b.mu = 0,
  b.sig = 1, c.alpha = 5, c.beta = 43)

Arguments

n.peo

the number of people to be generated

n.item

the number of items to be generated

thetas

a vector of ability parameters to be imported

a

a vector/number of a parameters to be imported

b

a vector of b parameters to be imported

c

a vector/number of item c parameters to be imported

theta.mu

the mean of the normal distribution from which thetas are generated

theta.sig

the sd of the normal distribution from which thetas are generated

a.mu

the log mean of the lognormal distribution from which a parameters are generated

a.sig

the log sd of the lognormal distribution from which a parameters are generated

b.mu

the mean of the normal distribution from which b parameters are generated

b.sig

the sd of the normal distribution from which b parameters are generated

c.alpha

the alpha parameter of the beta distribution from which c parameters are generated

c.beta

the beta parameter of the beta distribution from which c parameters are generated

Details

In generation, thetas are drawn from the normal distribution, a parameters from the lognormal distribution, b parameters from the normal distribution, and c parameters from the beta distribution. When parameters are imported, they are not drawn from the distribution.

Value

an irt object

See Also

Other commons: irt, prob

Examples

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# generate 10 people, 5 items
gen.irt(10, 5)
# generate data with given thetas
gen.irt(10, 5, thetas=seq(.1, 1, length.out=10)) 
# generate data with given iteme parameters (Rasch items)
gen.irt(10, 5, a=.588, c=0)