Applying the Rasch Growth Model (RGM) for the evaluation of achievement
trajectories
Abstract
Considerable interest lies in the growth in educational achievement that
occurs over the course of a child’s schooling. This paper demonstrates a
simple but effective approach for the comparison of growth rates,
drawing on a method first proposed some 80 years ago and applying it to
data from the Australian National Assessment Program. The methodology
involves the derivation of a ‘meta-metre’ – a quantitative mode of
variation in growth – which permits comparison between groups defined
by time-invariant characteristics. Emphasis is placed upon the novel
characteristics of the method and the valuable information it can
provide. Unlike complex modeling procedures, the approach provides a
parsimonious, easily-interpretable model of growth.