SNSequate (version 1.3-4)

eqp.eq: 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))

Value

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

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

Author

Jorge Gonzalez <[e-mail]>

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.

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)