Table B Contextualised model: Benefit in terms of child attainment at start of primary
school in months of development.
|
Pre-reading |
Language |
Early number | |
|
Effect Size in months |
Effect Size in |
Effect Size in months | |
|
Nursery classes________ |
3.66 |
6.29_________________ |
3.67 |
|
Playgroups____________ |
2.65____________________ |
7.26_________________ |
6.29____________________ |
|
Private day nurseries |
8.21_____________________ |
9.68_________________ |
8.64____________________ |
|
Nursery schools________ |
1.90____________________ |
6.45_________________ |
5.76____________________ |
|
Integrated centres_______ |
2.15____________________ |
8.07_________________ |
7.20____________________ |
|
LA day nurseries |
3.75 |
6.45 |
4.98 |
The value added figures on child progress are shown below. Here the effects for pre-school
providers are taken with LA day nurseries as the comparison group (this group had the smallest
effects in the value added models) and are again shown in terms of months of development.
Table C Value added model: Benefit in terms of child progress over the pre-school
period in terms of months of development. (LA day nurseries is the comparison group)
|
Pre-reading |
Language |
Early number | |
|
Effect Size in months |
Effect Size in months |
Effect Size in months | |
|
Nursery classes_________ |
3.70___________________ |
2.26_________________ |
0.27___________________ |
|
Playgroups_____________ |
0.75___________________ |
2.90_________________ |
2.43___________________ |
|
Private day nurseries |
3.28___________________ |
3.39_________________ |
2.22___________________ |
|
Nursery schools________ |
2.40___________________ |
2.74_________________ |
3.14___________________ |
|
Integrated centres_______ |
3.03___________________ |
4.52_________________ |
5.24___________________ |
The question of the effects that can be attributed to quality of pre-school provision is of interest.
Earlier, this paper gave analyses of quality and duration effects, where the quality measure is
derived from observational ratings (ECERS-E). These ratings of aspects of quality are one way
of getting a handle on this slippery topic.
Another approach is to consider the residual effects attributable to individual pre-school centres
after controlling for all measured child, family, home and contextual factors. These residuals
provide measures of effectiveness and can be regarded as the outcome of pre-school quality
differences. These quality differences are in turn the result of a range of differences between
pre-school centres. The advantage of this approach is that the residual centre effects can be
regarded as a proxy for the cumulative effect of all quality differences.
For pre-reading the range of centre residuals effects is 10.43 points on the pre-reading scale.
This is a difference between the best and the worst centre in a distribution that is approximately
normal. Let’s take the centre that is one standard deviation below the mean as an averagely bad
centre in terms of quality, and the centre that is one standard deviation above the mean as an
averagely good centre in terms of quality. The difference between these is 2 SD units, which is
4.2. This could be regarded as a measure of the effect size of quality (average bad compared
with average good). It is a relatively conservative estimate as it is considerably smaller than
comparing the very worst with the very best, and the levels of quality compared are ones that are
frequently present in the population of pre-school centres. This effect size for quality of 4.2 pre-
reading units is equivalent to 4.15 months of development.
Similar computations for language give an effect size for quality of 2.48 months of development,
and for early number concepts an effect size for quality of 3.36 months of development.
Finally, the relative effects of increasing family income versus increasing the time the child
attends pre-school are explored. This question is best considered where the duration of pre-
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