The graduates who completed the CEQ differ on
individual characteristics such as age and sex, have
undertaken courses which also differ in their
characteristics, and have graduated from institutions
which have distinct histories and missions. It is worth
noting, as Meyler did, that students judgements of
subjects are influenced by the size of the subject,
whether the subject is compulsory, and whether the
subject is quantitative. Since the current CEQ items
invite aggregated judgements about subjects, rather than
the totality of graduates course experiences, we
might expect to see substantial differences in the
ratings of different types of courses. The stratified
nature of the population suggests that we have a sample
of graduates that should be considered to have three
levels &endash; the individual, the course, and the
institution. Given that this is the case, the forms of
analysis that are reported above and that have been used
by most others who have researched this area are not
appropriate and that analytical tools that do recognise
the hierarchical nature of the sample should be used. One
such tool is HLM (Hierarchical Linear Modelling) .
We undertook a series of analyses to see if we could
identify differences between institutions when individual
and course level variables are separated. In order to
make these analyses tractable, we confined our attention
to the three South Australian universities and used a
subset of data of graduates from those institutions.
Under this three level model, it is argued that the score
of any individual is the result of an institutional
component, a course component, an individual component,
and error terms that account for unexplained variation at
each level.
At the level of individuals we used sex, age,
non-English speaking background (NESB) status, employment
status, and mode of study as explanatory variables. The
regression equation for this relationship is shown
below.
GSI = P0 + P1.Sex +
P2.Age + P3.Nesb + P4.Emp + P5.Mode + E
That is, an individuals GSI score can be
understood as depending upon his or her own
characteristics of sex, age, NESB status, employment
status, and mode of study, and that there is an intercept
term (P0) that is a result of variables which operate at
the course and institutional levels.
At course and institutional levels we did not use
explanatory variables. We included only proxy categorical
(dummy) variables to separate the influences of the
different broad fields of study and the different
universities. In estimating the parameters in the
following equations, with data from N sources, N-1
parameters can be estimated so one parameter (for a
course type or institution) must be omitted from the
estimation. (In the equations below, the omitted
parameters are shown in brackets). However, an individual
must be a member of one, and only one, category so the
omitted parameter must be the complement of the sum of
the estimated ones. The course level regression equation
was therefore:
P0 = B00 + B01.AgSci +
B02.Arch + B03.HSS + B04.Bus + B05.Educ + B06.Eng +
B07.Eng + B08.Law [ + B09.MaSci] +
R0
Thus the intercept term used in the first level
equation (P0) is the result of the particular course type
that the individual completed, an error term to represent
unexplained variance (R0), and an intercept term (B00)
that reflects variation at the third or institutional
level.
For the institutional level, the regression equation
was:
B00 = G000 + G001.Flin
+ G002.Adel [ + G003.UniSA] +
U0
It should be noted that the three levels of the model
are related through intercept terms. At the individual
level, there is an intercept P0, and it is the criterion
variable of the course level equation. Its intercept
term, B00, is the criterion variable in the third level
equation. In that equation, the parameters of interest to
us are the coefficients of the categorical variables for
each of the institutions. Those parameters tell us about
the relative standings of the three institutions when the
hierarchical nature of the sample is modelled and when
variables at the individual and course levels are taken
into account. Table 4 shows a summary of the results of
the hierarchical analyses completed using HLM.
Table 4: Summary
results of the hierarchical analysis of data from the
three South Australian universities
|
Fixed
Effect
|
Coefficient
|
Standard
Error
|
T-ratio
|
Sig
|
|
Level
3 effects
|
|
|
|
|
|
FLIN
|
484.25
|
13.04
|
4.58
|
**
|
|
ADEL
|
472.72
|
5.56
|
8.66
|
**
|
|
UNISA
|
461.14
|
5.12
|
7.15
|
**
|
|
Level
2 effects
|
|
|
|
|
|
AGSCI,
B01
|
-0.50
|
14.58
|
-0.03
|
|
|
ARCH,
B02
|
-3.11
|
15.89
|
-0.20
|
|
|
HSS,
B03
|
26.60
|
11.84
|
2.25
|
**
|
|
BUS,
B04
|
-14.32
|
12.17
|
-1.18
|
|
|
EDUC,
B05
|
25.68
|
12.82
|
2.00
|
*
|
|
ENG,
B06
|
-18.53
|
13.50
|
-1.37
|
|
|
MED,
B07
|
-9.79
|
12.17
|
-0.80
|
|
|
LAW,
B08
|
0.50
|
14.58
|
0.03
|
|
|
MASCI,
B09
|
6.88
|
12.04
|
0.57
|
|
|
Level
1 effects
|
|
|
|
|
|
SEX,
P1
|
4.77
|
3.29
|
1.45
|
|
|
AGE,
P2
|
1.15
|
0.18
|
6.35
|
**
|
|
NESB,
P3
|
-8.04
|
3.99
|
-2.02
|
**
|
|
UNEMP,
P4
|
-10.91
|
5.35
|
-2.04
|
**
|
An * in the
Significance column indicates p<0.10 while **
indicates p<0.05
From the hierarchical analyses, we found that mode of
study was not significant and has been dropped from the
model. Sex was only marginally significant, but we have
chosen to leave it in the model as it assists in
explaining some of the features that emerge from the
analyses. To estimate the GSI of any individual the
separate regression equations with their estimated
parameters can be combined. For any individual, the
institutional score is taken and added to it is the broad
field of study score, and then the individual
characteristic variable scores.
GSI = Inst + BFStud +
3.81 Sex + 0.92 Age - 6.43 Nesb - 8.73 Emp + E + R0 +
U0
It is instructive to compare course and
institutional means found from multilevel analysis with
those found from earlier methods.
Course type
performances
When raw means of graduates from each of the nine
broad fields of study are computed, no allowance is made
for the characteristics of graduates from those courses.
For example, graduates of engineering courses are younger
than those of education awards and more of them are
males. In the multilevel analysis, it is apparent that
younger graduates make harsher judgements of course
quality than do older ones, and males tend to make
harsher judgements than do females. Table 5 shows the
deviation of the raw mean from 500 (the overall mean of
all graduates) and the course intercept from the
multilevel analysis. While for some course types there is
very little difference between the two measures of
perceived course quality, for others eg, Architecture
there are substantial differences. Architecture graduates
are predominantly male, younger than other graduates, and
experience greater difficulty in finding employment. Each
of these factors is associated with significantly lower
judgements of course quality. By not separating these
factors, Architecture courses are perceived to rate
poorly by comparison with others. For Education
graduates, there is a substantial difference between the
raw score deviation and the HLM intercept. This is
attributed to the low representation of NESB persons and
the difficulty gradates experience in finding
satisfactory employment as many find only part time and
short term contract work. However, when the influence of
individuals characteristics is removed, the
influence of the type of course on graduates
perceptions of course quality is shown to be little
different from the overall mean. We argue that when
institutions are comparing course types with each other,
it would be more sensible to use a measure that has
greater meaning and that has extracted from it influences
other than those due to the course itself.
Table 5: A comparison of Broad Field of Study
means (expressed as deviations from the overall mean)
with intercepts from multilevel analysis
|
|
AgSi
|
Arch
|
HSS
|
Bus
|
Educ
|
Eng
|
Med
|
Law
|
MaSci
|
|
Dev
from oall mean
|
11.50
|
-19.10
|
27.06
|
-14.29
|
7.08
|
-23.86
|
-16.91
|
-6.20
|
2.30
|
|
HLM
dev
|
-0.50
|
-3.11
|
26.60
|
-14.32
|
25.68
|
-18.53
|
-9.79
|
0.50
|
6.88
|
Institutional performance
measures
It has been argued earlier in this paper that
institutions can be compared using graduates raw
GSI scores, but we have argued that failing to correct
for course mix biases the measure. In the multilevel
analysis, we have found that there are individual
graduate characteristics that influence their judgements
about courses. In order to unpack the results of the
multilevel analysis, it is instructive to examine the
measures that are available. These measures are presented
in Table 6.
Table 6: A comparison of alternative
measures of institutional performance derived from the
GSI
|
Institution
|
Raw
mean GSI
|
Expected
GSI
|
Difference
(raw-expected)
|
Multilevel
intercept
|
|
Flinders
|
526.86
|
503.61
|
23.25
|
484.25
|
|
Adelaide
|
507.91
|
503.63
|
4.28
|
472.72
|
|
University
of SA
|
502.10
|
496.04
|
6.06
|
461.14
|
First, it should be noted that under the
analyses described above, the three South Australian
universities perform at or above the national average.
Indeed Flinders University performs well above it. Both
the University of Adelaide and the University of South
Australia perform slightly better than expected, but not
significantly so. On the measure corrected for course
mix, Flinders performs 19 points ahead of Adelaide.
However, when corrected for individual graduate
characteristics, its lead over Adelaide is reduced to
about 12 points. This is because Flinders graduates are
almost six years older than Adelaide graduates, it has a
greater proportion of women graduates, and a lower
proportion of NESB graduates. When Adelaide
graduates characteristics are considered, it has a
lead of 11 points over the University of South Australia.
|