M.estimate: M-estimator of scale of a trapezoidal fuzzy sample

In FuzzyStatTra: Statistical Methods for Trapezoidal Fuzzy Numbers

Description

This function calculates the M-estimator of scale with loss function given in M for a matrix of trapezoidal fuzzy numbers F. For computing the M-estimator, a method called “iterative reweighting” is used. The employed metric in the M-equation can be the 1-norm distance, the mid/spr distance or the (\varphi,θ)-wabl/ldev/rdev distance. The function first checks if the input matrix F is given in the correct form (tested by checkingTra).

Usage

M.estimate(F, M, est_initial, delta, epsilon, type, a = 1, b = 1, theta = 1/3)

Arguments

F	matrix of dimension n x 4 containing n trapezoidal fuzzy numbers characterized by their four values inf0,inf1,sup1,sup0. The function implicitly checks if the matrix is in the correct form (tested by checkingTra).
M	name of the loss function. It can be “Huber”, “Tukey” or “Cauchy”.
est_initial	initial scale estimate.
delta	number in (0,1). It is present in the M-equation.
epsilon	number >0. It is the tolerance allowed in the algorithm.
type	number 1, 2 or 3: if type==1, the 1-norm distance will be considered in the calculation of the M-estimator. If type==2, the mid/spr distance will be considered. By contrast, if type==3, the (\varphi,θ)-wabl/ldev/rdev distance will be used.
a	number >0, by default a=1. It is the first parameter of a beta distribution which corresponds to a weighting measure on [0,1] in the mid/spr distance or in the (\varphi,θ)-wabl/ldev/rdev distance.
b	number >0, by default b=1. It is the second parameter of a beta distribution which corresponds to a weighting measure on [0,1] in the mid/spr distance or in the (\varphi,θ)-wabl/ldev/rdev distance.
theta	number >0, by default theta=1/3. It is the weight of the spread in the mid/spr distance and the weight of the ldev and rdev in the (\varphi,θ)-wabl/ldev/rdev distance.

Details

See examples

Value

The function returns the value of the M-estimator of scale, which is a real number.

Note

In case you find (almost surely existing) bugs or have recommendations for improving the functions comments are welcome to the above mentioned mail addresses.

Author(s)

Asun Lubiano <[e-mail]>, Sara de la Rosa de Saa <[e-mail]>

See Also

checkingTra, Rho1Tra, DthetaphiTra, DwablphiTra

Examples

# Example 1:
F=SimulCASE1(100)
U=Median1norm(F)
est_initial=MDD(F,U,1)
delta=0.5
epsilon=10^(-5)
M.estimate(F,"Huber",est_initial,delta,epsilon,1)

FuzzyStatTra documentation built on May 2, 2019, 10:59 a.m.