Martin Caust
Selected graphs 5.2
The
major line is a model of the mean growth in Reading based
on the national 2008 NAPLAN averages at four age points. The
model is based on a Gompertz curve fitted to the four
points. By fitting curves to the points representing
+/- 1.96 SDs the upper and lower boundaries can also be modeled.
From the upper and lower lines the SDs can be generalised
for all ages. These SDs are plotted and show the general model of
reducing SD with age. The annual rates of change can also be
plotted. This rate peaks at about age 5, about one year before
the SD spread peaks (age 6 approx).
The thesis develops a model data set to represent a school system where
each Year level is notionally tested annually. This simple model
offers a more dynamic description of possible mean trends than do the
descriptions for each Year level seperately.