Evaluation of the Australian Wage Subsidy Special Youth ...

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5.5.3.2 The effect of sample reduction on the difference between SYETP and comparison
groups
Overall, in the previous section it can be seen that the effect of the sample reduction is
not equal on the treatment and the comparison groups’ profile for these characteristics
examined. This is crucial as the aim of later modelling of the treatment effect is the
comparison of the treatment and comparison groups. The effect of sample reduction on
the difference in profiles of the treatment and comparison groups is now explored. This
provides a different perspective on how the data reduction impacts on the analysis.
The contrast between the treatment and comparison group is summarised in the absolute
mean difference that is shown in Table 5.4. The first column of Table 5.4 gives the presample-
reduction differential while the second column is the post-sample-reduction
statistic. Statistically significant differences between these means are shown with a star
indicating a one percent level of significance. Almost all the differences are statistically
significant. However the differences between the treatment and comparison prior to
sample reduction are not the same as those present after sample reduction.
The lack of correspondence between the treatment and comparison group before sample
reduction is quite great. Table 5.4 shows the profile prior to sample reduction to be
markedly different for the treatment and comparison groups for certain characteristics,
and the scale of contrast can be illustrated by considering the figures underlying column 1
of Table 5.4. Far fewer of those who enter the SYETP were married in 1984 (3.9 per cent)
than amongst the comparison group (11.7 per cent). The educational profile differs for
those on SYETP compared to the comparison group. Fewer on SYETP have post-school
qualifications (15.5 per cent) than in the comparison group (26.7 per cent), while more of
those on SYETP have schooling of year 10 (36.1 per cent), year 11 (16.1 per cent) and 12
(19.4 per cent) than do those in the comparison group (at 29.9 per cent, 12.1 per cent and
15.1 per cent respectively). The work history profile of those who entered SYETP is also
quite different to that of the comparison group. The share of those on SYETP with work
experience of less than a year is 58.1 per cent, which contrasts strongly with the