FMPMonotonicityCheck: Utility function for checking FMP monotonicity

Description Usage Arguments Value Author(s) Examples

View source: R/FMPMonotonicityCheck.R

Description

Utility function for checking whether candidate FMP coefficients yield a monotonically increasing polynomial.

Usage

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FMPMonotonicityCheck(b, lower = -20, upper = 20, PLOT = FALSE)

Arguments

b

A vector of 8 polynomial coefficients (b) for m(θ)=b_0 + b_1 θ + b_2 θ^2 + b_3 θ^3 + b_4 θ^4 + b_5 θ^5 + b_6 θ^6 + b_7 θ^7.

lower, upper

θ bounds for monotonicity check.

PLOT

Logical (default = FALSE). If PLOT = TRUE the function will plot the original polynomial function for θ between lower and upper.

Value

increasing

Logical indicating whether function is monotonically increasing.

minDeriv

Minimum value of the derivative for the polynomial.

minTheta

Value of θ at derivative minimum.

Author(s)

Niels Waller

Examples

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## A set of candidate coefficients for an FMP model.
## These coefficients fail the test and thus
## should not be used with genFMPdata to generate
## item response data that are consistent with an 
## FMP model.
 b <- c(1.21, 1.87, -1.02, 0.18, 0.18, 0, 0, 0)
 FMPMonotonicityCheck(b)

fungible documentation built on Sept. 29, 2021, 1:06 a.m.