eqp.eq {SNSequate}

The equipercentile method of equating

Description

This function implements the equipercentile method of test equating as described in Kolen and Brennan (2004).

Usage

eqp.eq(sx, sy, X, Ky = max(sy))

Arguments

sx

A vector containing the observed scores on test X

sy

A vector containing the observed scores on test Y

X

Either an integer or vector containing the values on the scale to be equated.

Ky

The total number of items in test form Y to which form X scores will be equated

Details

The function implements the equipercentile method of equating as described in Kolen and Brennan (2004). Given observed scores sx and sy, the functions calculates

\varphi(x)=G^{-1}(F(x))

where F and G are the cdf of scores on test forms X and Y, respectively.

Value

A two column matrix with the values of \varphi() (second column) for each scale value x (first column)

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.

Kolen, M., and Brennan, R. (2004). Test Equating, Scaling and Linking. New York, NY: Springer-Verlag.

See Also

mea.eq, lin.eq, ker.eq

Examples

### Example from Kolen and Brennan (2004), pages 41-42:
### (scores distributions have been transformed to vectors of scores)

sx<-c(0,0,1,1,1,2,2,3,3,4)
sy<-c(0,1,1,2,2,3,3,3,4,4)
x<-2
eqp.eq(sx,sy,2)

# Whole scale range (Table 2.3 in KB)
eqp.eq(sx,sy,0:4)