PREp {SNSequate}

Percent relative error

Description

This function calculates the percent relative error as described in Von Davier et al. (2004).

Usage

PREp(eq, p)

Arguments

eq

An object of class ker.eq previously obtained using ker.eq.

p

The number of moments to be calculated.

Details

PREp (when equating form X to Y) is calculated as

\mbox{PREp}=100\frac{\mu_p(e_Y(X))-\mu_p(Y)}{\mu_p(Y)}

where \mu_p(Y)=\sum_k(y_k)^ps_k and \mu_p(e_Y(X))=\sum_j(e_Y(x_j))^pr_j. Similar formulas can be found when equating from Y to X.

Value

A matrix containing the PREp for both X to Y (first column) and Y to X (second column) cases.

Author(s)

Jorge Gonzalez [e-mail]

References

Gonzalez, J. (2014). SNSequate: Standard and Nonstandard Statistical Models and Methods for Test Equating. Journal of Statistical Software, 59(7), 1-30.

Von Davier, A., Holland, P., and Thayer, D. (2004). The Kernel Method of Test Equating. New York, NY: Springer-Verlag.

See Also

ker.eq

Examples

#Example: Table 7.5 in Von Davier et al. (2004)

data(Math20EG)
mod.gauss<-ker.eq(scores=Math20EG,kert="gauss", hx = NULL, hy = NULL,degree=c(2, 3),design="EG")
PREp(mod.gauss,10)