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Social Segregation in Schools : An International

Comparison

Stephen P. JENKINS (University of Essex)John MICKLEWRIGHT (University of Southampton)

Sylke V. SCHNEPF (University of Southampton)

29th General Conference IARIW

Joensuu, Finland, August 20 - 26, 2006

Paper presentedby Yves Flückiger (University of Geneva)

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Social Segregation in schools (defined as the uneven distribution across

schools of children of different social background) has been much discussed

in all OECD countries in recent years

This question is of interest for at least three reasons :

1. If it is true that children´s performance at school depends on their peers,

higher levels of social segregation lead to greater academic achievement

and thence to greater inequality in later-life outcomes

2. Excessive segregation may also threaten present-day social cohesion

3. Greater social segregation may even reduce average achievement levels

1. Introduction

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Using the data from the 2000 and 2003 rounds of the Programme of International Student Assessment (PISA), the authors compare the situation in England with that in 27 OECD countries involved in this survey

Their research significantly extends the analysis by Gorard and Smith (2004) based on the 2000 PISA round in at least five directions :

1) The authors use the 2000 and 2003 PISA rounds

2) They consider all OECD countries rather than only the EU-15

3) They consider other indices of segregation

4) They account for sampling variation by calculating standard errors and confidence intervals for their estimates of segregation indices

5) They use quantitative decomposition of segregation indices to explain the cross-national pattern observed

1. Introduction

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PISA collects information about 15 year old children and their school using a cross-national harmonized questionnaire

Combining the data from two PISA rounds has a major pay-off : sample sizes increase substantially. For England, the pooled sample used by the authors covers 314 schools and 7’886 children

A range of family background information is collected in PISA but the authors focus on parental occupation

From this information, the PISA organisers derive the two-digit international index of socio-economic position proposed by Ganzeboom et al. (1992)

The authors then measure the child´s social position is the higher of the two index values if both parents are present and the index value itself in the single parent case

2. Data

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The authors then transform each child´s index of social position into a variable with just two values : high and low

This is mainly because they use conventional measures of segregation and these require a binary classification of social background

Moreover the authors define high and low social position in each countries in terms of the national distribution of social position index values

High refers to having a value above the national median ; low refers to having a value equal or below this median

In order to check the sensitivity of their results to the choice of cut-off, the authors also reestimate their segregation measures using a number of alternative thresholds of the national distribution: the lower and upper quartile as well as the top decile

2. Data

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The authors use two indices of the unevenness of the distribution of social backgrounds across schools : the dissimilarity index D (proposed by Duncand & Duncan, 1955) and the square root index H (proposed by Hutchens, 2001 and 2004)

3. Methods and indices of segregation

Where :pi represents the number of children with low social position in school iri is the number of children with high social position in school iP and R : total number of children with low and high social position

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D represents the fraction of students with low social position that would to be moved in order that each school had the same proportion of students with low and high social position

H is the sum, over all schools, of each school´s shortfall from distributional evenness

As the two indices measure unevenness in a different way (D uses absolute differences while H uses proportionate differences) they may lead to different orderings of the countries

Using both indices enable the authors to check for the robustness of their results

As D does not satisfy the « transfer principle », the authors supplement their calculations of D and H by deriving the segregation curves for several countries

3. Methods and indices of segregation

H as the further advantage of being « additively decomposable » by subgroups of schools (for example private and state schools)

H can then be decomposed into two parts :

1. Segregation within private and state schools

2. Segregation between private and state schools

3. Methods and indices of segregation

Where: Hwithin : weighted sum of the segregation within each sectorHg : value of H calculated for all schools belonging to sector gHbetween : amount of segregation that would remain if there were no segregation within each school type

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Since PISA is a sample survey, any measure of segregation is subject to sampling variation

The authors estimate standard errors and confidence intervals for D and H applying the bootstrap method (400 replicate samples of school)

They also take into account the upward bias that may affect the measure of segregation indices based on sample survey but the results show that the number of schools seem to be sufficient enough to reduce bias to negligible levels

3. Methods and indices of segregation

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According to the estimates of D, segregation is the highest for country such as Austria, Germany and Hungary, each of which has secondary school systems with separate academic and technical school tracks

Among the countries with the lowest social segregation are the four Nordic countries: Norway, Sweden, Denmark and Finland

The results obtained do not change very much when using the H index instead of the D index (Pearson correlation index is equal to 0.97 and the Spearman rank correlation is equal to 0.96)

The confidence intervals around the estimate are quite wide in many cases due to the reduced size of the sample

These results are robust to different thresholds that may be used to define low and high social positions

4. Differences in social segregation across OECD countries

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Decomposing H index into within and between schools type elements seems to show that little of the social segregation may be attributed to the existence of private schooling

It can also be be proved that segregation in the private sector is far from being low… however this result should be treated with caution as the number of private schools in the sample is low ; hence, the estimate for Hprivate is subject to large sample variation

The share of total segregation that is accounted for the school type in England or in Scotland (around 20%) is larger than in other OECD countries

In this sense, the existence of private schools in England contributes to social segregation much more than in most other countries

5. The role of private schooling

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The last topic addressed by the paper concerns the choice of schools by parents and the choice of students by schools

PISA collects information from schools about their admissions practices

The survey also collects information from the children on why they attend their current school (it has been labelled « parental choice »)

The prevalence of parental choice for England (52% !) is greater than in any other countries

Parental choice is more prevalent in urban areas than in rural regions

By contrast, the prevalence of school choice is low in England compared to OECD standards

6. Choices of School and Students

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To investigate the impact of parental and school choices, the authors plot the values of H for the state sector in each country against the prevalence of these choices

The scatterplots suggest that school choice is an important factor

The correlation between school choice and social segregation is 0.58 and it raises to 0.72 without Japan (high prevalence of school choice but very low social segregation)

In contrast to this first result, figure 6 shows no association between parental choice and social segregation (the correlation coefficient is equal to 0.12)

6. Choices of School and Students

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This is a very important and interesting paper

It addresses very crucial socio-economic questions and it is a policy-oriented paper which is very useful for the politicians in charged of education

I have only few remarks and maybe some suggestions that could be helpful for the authors

1. My first remark is related to the defintion of social position which is defined using the Glanzboom approach

• According to me social segregation is a much more complex phenomenon and it am not sure that it can be reduced to one dimension only

• Morover, I am not convinced that using the highest index value of the two parents is a good way to treat social segregation

DISCUSSION

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2. My second remark refers to the segregation indices

• As pointed out by the authors, they are well suited to the two-groups case but social segregation could be better addressed by using a multi-group index such as the one used by Reardon

• This will increase the information hold in the index and it is a better way to treat this problem than using different thresholds

3. My third remark is related to the fact that if analyzing social segregation by school is very intereting in itself, politicians may want to know if segregated schools produce better overall performance for each indvidual student

• They also would like to know if the reduction in social segregation could lead to a more efficient education system and it would be very interesting to introduce these results in a DEA analysis of school efficiency

DISCUSSION

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4. My fourth remark concerns the relation between school choice and social segregation

• This is indeed a very important question, even more important if we could know the relation between social segregation and the school performance

• But we do not know how it works and how the school are choosing their students : are they choosing thus who have the highest social position and do they have the information to do such a selection ?

• We may also think that the school are choosing their students according to their results (which are in fact closely related to their social position)

• Thus I really believe that the results reported in the last sections of the paper should be treated with great caution as we do not know the model behind the segregationn process

DISCUSSION