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Why does Year Twelve retention differ between Australian states and territories?

Article Excerpt
Year Twelve retention rates have a number of well-known deficiencies that prevent proper comparisons of school completion between school systems. This paper compares secondary school completion rates across Australian states and territories from 1989 to 2002 and adjusts 'official' 2002 retention rates to take account of the acknowledged measurement problems. We identify a pattern of mismeasurement of national Year Twelve retention over the 1990s. We estimate that the Year Twelve retention rate was a particularly poor measure of national school completion in the early 1990s, when it appeared to peak in the official estimates. In contrast to the official figures, our adjusted measure of Year Twelve retention was no lower in the late 1990s than it had been in the early 1990s. Our findings suggest that governments should be cautious in using official Year Twelve retention rates as a measure of the performance of Australian school systems.

Keywords

educational policy

grade repetition

secondary school students

school holding power

performance indicators

school entrance age

Introduction

Retention at school to Year Twelve has traditionally been used as an indicator of school system performance in Australia. For example, the 1989 National Report on Schooling in Australia indicated that state and Commonwealth ministers for education had 'agreed to work towards a national Year Twelve retention rate of sixty-five per cent by the early 1990s' (Australian Education Council, 1991, p. 8).

The Year Twelve retention rate is measured as the number of students in Year Twelve in a given calendar year divided by the number of students who were in the first year of secondary school when that Year Twelve cohort commenced secondary school. While comparisons of retention rates across jurisdictions have always been made, official publications have repeatedly pointed to a list of factors that limit their usefulness, such as:

* population changes, including international and interstate migration

* the effect of full fee-paying overseas students at upper secondary level

* Year Twelve repetition

* the availability of part-time school study options

* the effect of alternatives to school education, most notably vocational courses available through Technical and Further Education (TAFE) institutions

* the different age-grade structures in the states (Steering Committee for the Review of Commonwealth/State Service Provision, 2000, pp. 66-7). (1)

In response to these deficiencies, governments have developed alternative measures of school participation and completion, such as 'attainment rates' by age nineteen and 'full-time participation' rates, which include participation in full-time study or work and jointly in part-time work and study (Ministerial Council on Education, Employment, Training and Youth Affairs, 2000). (2) Nevertheless, we will argue that these indicators require just as careful interpretation as differences in retention rates across jurisdictions, because the different age-grade structures in jurisdictions have similar effects on alternative participation indicators to their effect on retention rates.

This paper estimates the impact of the confounding influences identified above on retention comparisons to assess their importance. The first two factors identified above are handled through adjustments to the estimated retention rates that build in changes in the school-age population. (3) The impact of grade repetition is estimated from available Australian Bureau of Statistics (ABS) data in conjunction with regression analysis. The role of the last three factors is also assessed with the regression analysis.

The second section describes the methodology used here to analyse the problems associated with retention rates and quantify their effects and presents adjusted estimates that take account of these effects. The third section uses these results to re-assess what happened to national retention rates over the 1990s. The fourth section discusses these estimates in the context of current directions in school system performance indicators. The policy implications of our results are discussed in the conclusion.

How to adjust to retention rates

The 'official' Year Twelve retention rates produced by the ABS are estimates of the proportion of any cohort who commence secondary school and proceed to Year Twelve in the minimum possible number of years in a jurisdiction. Secondary school commences in Year Seven in New South Wales, Victoria, Tasmania and the Australian Capital Territory. It commences in Year Eight in Queensland, South Australia, Western Australian and the Northern Territory. Consequently, the calendar year in which the denominator is measured varies between jurisdictions for any Year Twelve retention figure in a calendar year.

Most of the data used in this paper are taken from the National Schools Statistics Collection (NSSC), which is published by the ABS in Schools, Australia (Cat. No. 4221.0). (4) There are two particular limitations in the NSSC data for the analysis undertaken below. First, the data do not allow identification of the prevalence of Year Twelve repetition. Second, the data relate primarily to full-time students. Since both of these factors are forms of school participation that individuals may choose and their incidence has reportedly changed over time, their mismeasurement in these data might affect the validity of the inferences drawn here. Attempts to estimate rates of repetition and part-time study from the published data are described below.

The next three sub-sections describe the various adjustments we make to the official ABS retention rate estimates anticipated in the introduction: the first describes the adjustment to account for population changes; the second how we account for Year Twelve repetition; and the third the regression results that lie behind each of the adjustments required for TAFE study, part-time study and differences in age-grade structures between jurisdictions.

Adjustments for population changes

We make three adjustments to the standard retention rate definition used by the ABS to produce estimates that are more consistent across jurisdictions and to minimise the effects of departures or additions on the cohort through either grade repetition or migration, drawing on data published by ABS in Population by Age and Sex (1985-2002).

First, for all jurisdictions, retention rates are estimated by dividing the number of Year Twelve students in calendar year t with the number of Year Eight students in calendar year t minus four (in jurisdictions with six years of secondary school, the 'official' estimate uses t minus five). This changes marginally the estimated retention rates for those jurisdictions where secondary school commences in Year Seven, but leaves unchanged the estimates for jurisdictions where it commences in Year Eight.

Second, only those Year Eight students aged twelve to fifteen years inclusive are counted in the denominator (these ages represented 99.8 per cent of Year Eight students in Australia in 1998) and only those Year Twelve students aged sixteen to nineteen in the numerator (these ages represented 98.8 per cent of Year Twelve students four years later in 2002). (5)

Third, the estimates are adjusted for changes in the population of the relevant age cohorts in jurisdictions over these years. That is, population growth in each Year Eight single year of age...

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