ICAOD: FIM_logistic – R documentation

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FIM_logistic

Fisher Information Matrix for the 2-Parameter Logistic (2PL) Model

Description

It provides the cpp function for FIM for the model ~1/(1 + exp(-b *(x - a))). In item response theory (IRT), a is the item difficulty parameter, b is the item discrimination parameter and x is the person ability parameter.

Usage

FIM_logistic(x, w, param)

Arguments

`x`	Vector of design points.
`w`	Vector of design weight. Its length must be equal to the length of `x` and `sum(w) = 1`.
`param`	Vector of values for the model parameters `c(a, b)`.

Details

It can be shown that minimax and standardized D-optimal designs for the 2PL model is symmetric around point aM = (aL + aU)/2 where aL and aU are the lower bound and upper bound for parameter a, respectively. In ICA.control, arguments sym and sym_point can be used to specify aM and find accurate symmetric optimal designs.

Value

Fisher information matrix.

Examples

FIM_logistic(x = c(1, 2), w = c(.5, .5), param = c(2, 1))

ICAOD

Optimal Designs for Nonlinear Statistical Models by Imperialist Competitive Algorithm (ICA)

v1.0.1

GPL (>= 2)

Authors

Ehsan Masoudi [aut, cre], Heinz Holling [aut], Weng Kee Wong [aut], Seongho Kim [ctb]

Initial release