The Longitudinal Study of Australian Children Annual statistical report 2015

Introduction

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Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC) is Australia's first nationally representative longitudinal study of child development. The purpose of the study is to provide data that enable a comprehensive understanding of development and life-course trajectories within Australia's current social, economic and cultural environment. The longitudinal nature of the study enables researchers to examine the dynamics of change through the life course as children develop, and to go beyond the static pictures provided by cross-sectional statistics. The study thereby gives policy-makers and researchers access to quality data about children's development in the contemporary Australian environment.

The study was initiated and is funded by the Australian Government Department of Social Services, and is conducted in partnership with the Australian Institute of Family Studies (AIFS) and the Australian Bureau of Statistics (ABS). A consortium of leading researchers and experts from universities and research agencies provide advice to the study.

This is the sixth volume in the LSAC Annual Statistical Report series, which uses data from the first five waves of the study. The purpose of these reports is to provide a snapshot of some of the data from the study and to address policy-relevant questions about aspects of Australian children's lives and development. The report makes use of the longitudinal nature of LSAC data to describe the dynamics of change as children develop, and how their families and lives change as they grow older.

The first section of this introductory chapter provides a brief overview of LSAC, the second describes the analytical approaches used throughout the main chapters of the report, and the third section introduces the subpopulation groups that are used for comparisons in some chapters. The chapter ends with summary tables comprising a glossary of LSAC terms, statistical indicators, and the scales and measures used throughout the report.

1.1 About the study

Study design

The LSAC study has an accelerated cross-sequential design, with two cohorts of children of differing ages at the start of the study. One of the advantages of this type of design is that it provides data on later developmental pathways and outcomes before the younger cohort of the two matures. From Wave 3 there is data on children of the same age from both cohorts at different time points.

The B (baby”) cohort was aged 0-1 years at the beginning of the study (born between March 2003 and February 2004); and the K (“kindergarten”) cohort was aged 4-5 years at the beginning of the study (born between March 1999 and February 2000).

The first wave of data collection took place in 2004, with subsequent main waves every two years. In 2005 (Wave 1.5), 2007 (Wave 2.5) and 2009 (Wave 3.5), parents were also asked to complete a between-waves mail survey. In 2011 (Wave 4.5), the between-wave data collection changed from a paper-based questionnaire to an Internet-based form for respondents to report changes in contact details to aid tracking. Table 1.1 summarises the ages and sample sizes for the two cohorts across the first five main waves of the study.

As mentioned, this design means that from the third wave of the study, the children's ages overlap; that is, children were aged 4-5 years both in the first wave for the K cohort and in the third wave for the B cohort. In covering the first five waves of the study, this report includes data on children between the ages of 0 and 13 years.

Table 1.1: Age ranges and numbers of children, B and K cohorts, Waves 1-5
Wave 1
(2004)
Wave 2
(2006)
Wave 3
(2008)
Wave 4
(2010)
Wave 5
(2012)

Notes: This table presents the numbers of children who responded at each wave.

B cohort 0-1 year
5,107
2-3 years
4,606
4-5 years
4,386
6-7 years
4,242
8-9 years
4,085
K cohort 4-5 years
4,983
6-7 years
4,464
8-9 years
4,331
10-11 years
4,169
12-13 years
3,956

Respondents and collection methods

The use of multiple respondents in LSAC provides a rich picture of children's lives and development in various contexts. Across the first five waves of the study, data were collected from:

  • parents of the study child:1
    • Parent 1 (P1)—defined as the parent who knows the most about the child (not necessarily a biological parent);2
    • Parent 2 (P2), if there is one—defined as another person in the household with a parental relationship to the child, or the partner of Parent 1 (not necessarily a biological parent); and
    • a parent living elsewhere (PLE), if there is one—a parent who lives apart from Parent 1 but who has contact with the child;
  • the study child;
  • carers/teachers (depending on the child's age); and
  • interviewers.

In earlier waves of the study, the primary respondent was the child's Parent 1. In the majority of cases, this was the child's biological mother, but in a small number of families this was someone else who knew the most about the child. Since Wave 2, the K cohort children have answered age-appropriate interview questions, and from Wave 4 they have also answered a series of self-complete questions. The B cohort children answered a short set of interview questions in Wave 4 for the first time. As children grow older, they are progressively becoming the primary respondents of the study.

A variety of data collection methods are used in the study, including:

  • conducting face-to-face interviews:
    • on paper; and
    • by computer-assisted interview (CAI);
  • filling in self-complete questionnaires:
    • during interview (paper forms, computer-assisted self-interviews (CASI) and audio computer-assisted self-interviews (ACASI);
    • on leave-behind paper forms;
    • on mailout paper forms; and
    • on Internet-based forms;
  • physically measuring the child, including height, weight, girth, body fat and blood pressure;
  • directly assessing the child's vocabulary and cognition;
  • completing time use diaries;
  • conducting computer-assisted telephone interviews (CATI); and
  • linking to administrative or outcome data (e.g. Medicare, MySchool).

The interviews and questionnaires include validated scales appropriate to the children's ages (see section 1.4 for a list of some of the scales used in this report).

Sampling and survey design

The sampling unit for LSAC is the study child. The sampling frame for the study was the Medicare Australia (formerly Health Insurance Commission) enrolments database, which is the most comprehensive database of Australia's population, particularly of young children. In 2004, approximately 18,800 children (aged 0-1 or 4-5 years) were sampled from this database, using a two-stage clustered design. In the first stage, 311 postcodes were randomly selected (very remote postcodes were excluded due to the high cost of collecting data from these areas). In the second stage, children were randomly selected within each postcode, with the two cohorts being sampled from the same postcodes. A process of stratification was used to ensure that the numbers of children selected were roughly proportionate to the total numbers of children within each state/territory, and within the capital city statistical districts and the rest of each state. The method of postcode selection took into account the number of children in the postcode; hence, all the potential participants in the study Australia-wide had an approximately equal chance of selection (about one in 25).3

Response rates

The 18,800 families selected were then invited to participate in the study. Of these, 54% of families agreed to take part in the study (57% of B cohort families and 50% of K cohort families). About 35% of families declined to participate (33% of B cohort families and 38% of K cohort families), and 11% of families could not be contacted (e.g. because the address was out-of-date or only a post office box address was provided) (10% of B cohort families and 12% of K cohort families).

This resulted in a nationally representative sample of 5,107 0-1 year olds and 4,983 4-5 year olds who were Australian citizens or permanent residents. Table 1.2 presents the response rates for each of the five main waves.

Table 1.2: Response rates, main waves, B and K cohorts, Waves 1-5
Wave 1 Wave 2 Wave 3 Wave 4 Wave 5

Notes: This table refers to the numbers of parents who responded at each wave. Percentages based on weighted data. a The available sample excludes those families who opted out of the study between waves. b B cohort: different numbers of parents and their children responded at Wave 5. (There were eight cases where a child interview was completed and the main interview with the parents was not.) c K cohort: different numbers of parents and their children responded at Wave 3 (in one case a parent interview was completed and the interview with the study child was not), Wave 4 (in five cases a child interview was completed and the main interview with the parents was not) and Wave 5 (in four cases a child interview was completed and the main interview with the parents was not).

B cohort
Number of responses 5,107 4,606 4,386 4,242 4,077 b
Response rates of Wave 1 (%) 100.0 90.2 85.9 83.0 80.0
Response rates of available sample (%) a - 91.2 88.2 86.0 83.5
K cohort
Number of responses 4,983 4,464 4,332 c 4,164 c 3,952 c
Response rates of Wave 1 (%) 100.0 89.6 86.9 83.6 79.4
Response rates of available sample (%) a - 90.9 89.7 87.2 83.5
Total
Number of responses 10,090 9,070 8,718 8,406 8,029
Response rates of Wave 1 (%) 100.0 89.9 86.4 83.3 79.7
Response rates of available sample (%) a - 91.1 89.0 86.6 83.5

1.2 Analyses presented in this report

This report includes data from the first five main waves of the study, though given the breadth and depth of topics included in the study, chapters in this report do not necessarily use data from all five waves and/or both cohorts.

Each chapter addresses a series of policy-relevant questions using descriptive statistical analyses. In answering these questions, chapters generally take one or more of the following approaches:

  • comparisons between subpopulation groups (summarised in section 1.3) on the various aspects of children's environments and development; and
  • examinations of trends across waves as children get older.

Weighting and survey analysis

Sample weights (for the study children) have been produced for the study dataset in order to reduce the effect of bias in sample selection and participant non-response (Cusack & Defina, 2014; Daraganova & Sipthorp, 2011; Misson & Sipthorp, 2007; Sipthorp & Misson, 2009; Soloff, Lawrence, & Johnstone, 2005; Soloff, Lawrence, Misson, & Johnstone, 2006). When these weights are used in the analysis, greater weight is given to population groups that are under-represented in the sample, and less weight to groups that are over-represented in the sample. Weighting therefore ensures that the study sample more accurately represents the sampled population.

These sample weights have been used in analyses presented throughout this report. Cross-sectional or longitudinal weights have been used when examining data from more than one wave. Analyses have also been conducted using Stata® svy (survey) commands, which take into account the clusters and strata used in the study design when producing measures of the reliability of estimates.

Key points to be noted

Parent 1 is defined as the child's primary caregiver or the parent who knows the child best. The majority of Parent 1 respondents were mothers (i.e. at all waves, more than 95% of Parent 1 respondents have been women and the majority of Parent 2 respondents have been men).

Parent 1 for each study child was defined by the family at Wave 1. At subsequent waves, the preference, where possible, has been to retain the same person as Parent 1 to maintain the longitudinal consistency of the data. However, if Parent 1 no longer resides with the child or is temporarily away, Parent 2 of the previous wave becomes Parent 1. If both Parent 1 and Parent 2 do not reside with the child or are temporarily away, then a new Parent 1 (the best person to ask about the child's health, development and care) is assigned. Thus, Parent 1 and Parent 2 are sometimes not the same person in each wave, with different parents or guardians potentially occupying different roles at each wave.

Unless specifically noted, all references to the child's “household” or “family” are to those of Parent 1, and do not include any other household or family the child may have with a parent living elsewhere. Similarly, unless specified in the chapter, any reference to “parents” is to Parent 1 and Parent 2, not to parents living elsewhere. In some chapters, data are reported for mothers and fathers rather than for Parent 1 and Parent 2.

Some chapters compare responses to particular questions across waves. In some cases, these questions were collected using different methods in different waves (e.g. by interview in one wave and by self-complete questionnaire in another).

1.3 Subpopulation groups

This section introduces the subpopulation groups that are used in some of the chapters in this report. Most of these subpopulation groups were introduced in detail in the LSAC Annual Statistical Report 2010 (AIFS, 2011), and are summarised in Table 1.3 (child characteristics) and Table 1.4 (parent and family characteristics). The percentages shown in these three tables are based on weighted data (as described in section 1.2).

Child characteristics

The child characteristics at the first five waves are summarised in Table 1.3.

Table 1.3: Child characteristics, B and K cohorts, Waves 1-5
Subpopulation categories B cohort K cohort
Wave 1
(0-1 year)
(%)
Wave 2
(2-3 years)
(%)
Wave 3
(4-5 years)
(%)
Wave 4
(6-7 years)
(%)
Wave 5
(8-9 years)
(%)
Wave 1
(4-5 years)
(%)
Wave 2
(6-7 years)
(%)
Wave 3
(8-9 years)
(%)
Wave 4
(10-11 years)
(%)
Wave 5
(12-13 years)
(%)

Notes: Percentages based on weighted data. a Recorded at Wave 1. b Questions about whether the study child had a disability or medical condition were asked differently in Wave 1 so these data are not included here. c Weight status is based on body mass index. It was not calculated at Wave 1 for the B cohort.

Child gender a
Boys 51.2 51.1 51.1 51.1 51.2 51.2 51.3 51.3 51.2 51.8
Girls 48.8 48.9 48.9 48.9 48.8 48.8 48.7 48.7 48.8 48.2
No. of observations 5,107 4,606 4,386 4,242 4,085 4,983 4,464 4,332 4,169 3,956
Child birth order
Oldest child 0.2 19.6 29.1 31.4 33.2 28.8 31.4 32.9 34.6 36.3
Middle child/Twin 1.8 13.1 19.6 21.7 22.3 18.4 20.5 21.4 21.6 20.5
Youngest child 58.9 47.4 39.9 37.4 35.6 41.4 38.5 37.1 35.2 33.7
Only child 39.1 19.9 11.4 9.5 9.0 11.5 9.6 8.6 8.6 9.5
No. of observations 5,107 4,606 4,386 4,242 4,077 4,983 4,464 4,331 4,169 3,951
Main language spoken at home by child a
English 87.2 87.9 87.0 86.8 89.2 86.0 85.2 86.1 85.9 88.7
Not English 12.8 12.1 13.0 13.2 10.8 14.0 14.8 13.9 14.1 11.3
No. of observations 5,104 4,603 4,384 4,239 4,084 4,983 4,464 4,331 4,164 3,956
Child Indigenous status a
Indigenous 4.9 5.1 4.9 5.2 4.4 3.9 3.7 3.7 3.8 2.9
Non-Indigenous 95.1 94.9 95.1 94.8 95.6 96.1 96.3 96.3 96.2 97.1
No. of observations 5,107 4,606 4,386 4,242 4,085 4,981 4,462 4,329 4,167 3,956
Child has a disability or medical condition b
Yes - 5.9 8.6 5.4 4.1 - 11.1 7.7 6.2 4.7
No - 94.1 91.4 94.6 95.9 - 88.9 92.3 93.8 95.3
No. of observations - 4,606 4,386 4,242 4,047 - 4,464 4,331 4,164 3,913
Child weight status c
Underweight - 5.3 6.5 5.4 5.1 5.2 5.1 5.5 5.9 6.7
Normal weight - 71.3 69.7 73.8 71.1 74.2 75.2 69.5 65.6 65.7
Overweight or obese - 23.4 23.8 20.8 23.9 20.6 19.7 25.0 28.5 27.5
No. of observations - 4,522 4,324 4,181 3,998 4,934 4,423 4,289 4,018 3,803
Child gender

Parent 1 reported the child's gender at Wave 1.

Child birth order

At each wave, the birth order of the study child was determined based on the number of younger siblings and older siblings in the household. The birth order of the study child was classified as the oldest child, middle child or twins, youngest child or only child in the household.

Main language spoken at home by child

At Wave 1, Parent 1 respondents were asked whether they mainly spoke English or a language other than English at home. Languages were classified according to the Australian Standard Classification of Languages (ABS, 2005), and these were summarised into English or non-English languages.

Child has a disability or medical condition

At each of Waves 2 to 5, Parent 1 respondents were asked whether each household member had a medical condition or disability that had lasted 6 months or more, while being shown a prompt card with a list of conditions such as sight problems; hearing problems; blackouts, fits or loss of consciousness; difficulty learning or understanding things; and difficulty gripping things.

Child weight status

At each wave (except Wave 1 for the B cohort), interviewers measured the children's weight and height, and these measurements were used to calculate children's body mass index (BMI). The children were then classified as overweight or obese (Cole, Bellizzi, Flegal & Dietz, 2000), underweight (Cole, Flegal, Nicholls, & Jackson, 2007) or of normal weight. Children in the B cohort at Wave 1 were not measured because of the technical difficulties of measuring infants' height and weight.4

Child Indigenous status

Parent 1 respondents identified at Wave 1 whether the study child was of Aboriginal and/or Torres Strait Islander background. These results were summarised into a measure of whether the child was Indigenous or non-Indigenous.

Parent and family characteristics

The parent and family characteristics at the first five waves are summarised in Table 1.4.

Table 1.4: Parent and family characteristics, B and K cohorts, Waves 1-5
Subpopulation categories B cohort K cohort
Wave 1
(0-1 year)
(%)
Wave 2
(2-3 years)
(%)
Wave 3
(4-5 years)
(%)
Wave 4
(6-7 years)
(%)
Wave 5
(8-9 years)
(%)
Wave 1
(4-5 years)
(%)
Wave 2
(6-7 years)
(%)
Wave 3
(8-9 years)
(%)
Wave 4
(10-11 years)
(%)
Wave 5
(12-13 years)
(%)

Notes: Percentages based on weighted data. a Family socio-economic position is not currently available at Wave 5, it will be developed based on the new occupation codes in the future.

Household structure
Two biological parents 88.9 85.7 82.3 78.6 76.5 81.7 79.0 75.2 72.3 72.0
Single biological parent 10.4 13.1 14.0 15.8 15.9 14.8 16.6 16.7 18.3 17.9
Biological parent and step-parent 0.1 0.5 2.1 3.2 4.7 2.3 2.9 4.5 5.2 6.7
Two non-biological parents 0.2 0.2 0.2 0.3 0.3 0.4 0.5 0.4 0.5 0.4
Biological parent and other parent 0.2 0.3 1.2 2.0 2.4 0.6 0.8 3.0 3.5 2.5
One non-biological parent 0.1 0.1 0.3 0.1 0.1 0.2 0.2 0.2 0.3 0.2
No. of observations 5,107 4,606 4,386 4,238 4,077 4,983 4,464 4,331 4,150 3,952
Family socio-economic position a
Lowest 25% 28.6 31.2 31.5 32.9 - 28.6 30.3 31.5 32.1 -
Middle 50% 48.9 47.9 47.8 46.7 - 50.0 48.8 48.8 48.4 -
Highest 25% 22.5 20.9 20.7 20.4 - 21.4 20.9 19.7 19.6 -
No. of observations 5,092 4,602 4,382 4,215 - 4,965 4,458 4,327 4,124 -
Number of siblings in the household
None 39.1 19.9 11.4 9.5 9.0 11.5 9.6 8.6 8.6 9.5
One 36.4 47.3 46.3 43.6 42.5 47.5 43.9 42.5 42.5 43.4
Two or more 24.5 32.8 42.3 46.9 48.5 41.0 46.5 48.9 48.9 47.1
No. of observations 5,107 4,606 4,386 4,242 4,077 4,983 4,464 4,331 4,164 3,951
Main language spoken at home by Parent 1
English 83.1 83.7 83.1 82.8 85.6 82.5 81.6 82.7 82.6 84.8
Not English 16.9 16.3 16.9 17.2 14.4 17.5 18.4 17.3 17.4 15.2
No. of observations 5,107 4,606 4,386 4,238 4,077 4,983 4,464 4,328 4,146 3,952
Parent 1's country of birth
Overseas 20.0 22.7 23.2 23.4 22.0 23.3 24.2 23.5 23.5 22.5
Australia/NZ 80.0 77.3 76.8 76.6 78.0 76.7 75.8 76.5 76.5 77.5
No. of observations 5,107 4,606 4,386 4,242 4,077 4,982 4,463 4,327 4,159 3,952
Parent 1's education level
University degree or higher 29.1 28.3 29.6 30.0 33.4 24.1 24.4 25.1 25.8 28.7
Less than university degree 70.9 71.7 70.4 70.0 66.6 75.9 75.6 74.9 74.2 71.3
No. of observations 5,107 4,606 4,386 4,242 4,085 4,983 4,464 4,331 4,164 3,956
Both parents' education level
At least one parent has a university degree (or higher) 37.5 36.9 38.4 38.9 42.4 33.9 34.3 35.0 35.3 38.8
Neither parent has a university degree 62.5 63.1 61.6 61.1 57.6 66.1 65.7 65.0 64.7 61.2
No. of observations 5,104 4,604 4,385 4,240 4,075 4,979 4,463 4,329 4,163 3,948
Parent 1's employment
Employed 47.6 55.5 61.0 64.3 71.1 55.3 63.9 70.9 72.3 76.9
Unemployed 3.4 3.3 2.3 3.2 3.1 4.3 3.4 2.9 2.8 2.9
Not in the labour force 49.0 41.3 36.7 32.6 25.8 40.4 32.7 26.1 25.0 20.2
No. of observations 5,096 4,606 4,383 4,233 4,070 4,972 4,463 4,330 4,162 3,948
Jobless family
No 87.0 87.4 89.0 89.1 90.6 86.7 89.1 91.1 89.9 91.4
Yes 13.0 12.6 11.0 10.9 9.5 13.2 10.9 9.0 10.1 8.6
No. of observations 5,104 4,606 4,383 4,240 4,077 4,977 4,463 4,330 4,166 3,950
Region of residence
Metropolitan 66.5 62.6 64.9 63.6 62.8 63.7 65.9 62.9 62.4 62.0
Non-metropolitan 33.5 37.4 35.1 36.4 37.2 36.3 34.1 37.1 37.6 38.0
No. of observations 5,107 4,606 4,378 4,231 4,079 4,983 4,464 4,324 4,163 3,952
Neighbourhood disadvantage
Disadvantaged 27.5 31.1 30.8 30.3 28.7 28.2 31.0 30.8 30.2 30.5
Non-disadvantaged 72.5 68.9 69.2 69.7 71.3 71.8 69.0 69.2 69.8 69.5
No. of observations 5,107 4,606 4,386 4,240 4,077 4,983 4,464 4,331 4,168 3,951
Household structure

The household structure was classified using the demographic information of Parent 1's and Parent 2's gender, relationship to the study child and presence at each wave. The “two-biological parent” households refer to children's primary households that include two biological parents (a mother and a father). The “single-biological parent” households refer to children's primary households in which the study child lived with one biological parent only (Parent 2 was absent at the wave). Most of the single parents were single mothers (97%). The “one biological and step-parent” households include households where the study child lived with a biological parent and a step, adoptive or foster parent—the vast majority of these children lived in households with a biological mother and a step-father.

The “two non-biological parents” and “one non-biological parent” households include those headed by adoptive parents, grandparents or other relatives, and foster parents. The “biological and other parents” household refer to children's primary household where there was a biological parent and an unrelated adult or a relative to the study child (e.g. grandparent). This “unrelated adult” was usually the cohabiting (e.g. legal spouse, rather than married) partner to the biological parent.

Family socio-economic position

The measure of family socio-economic position (SEP), developed by Blakemore, Strazdins, and Gibbings (2009), uses information about combined annual family income, educational attainment of parents and parents' occupational status to summarise the social and economic resources available to families. The standardised SEP scores have been divided into quartiles and summarised into the lowest 25%, the middle 50% and the highest 25%.

Number of siblings in the household

At each wave, Parent 1 provides details about all household members, including the study child's siblings. Siblings include biological, adopted, foster, step- and half-siblings. Children may also have siblings who do not live in their household, but these siblings are not included here.

Main language spoken at home by Parent 1

The language spoken by Parent 1 is classified using the same approach described for the study children above.

Parent 1's country of birth

Parent 1 is grouped into “Australia or New Zealand born” or “born overseas” based on their country of birth provided at Wave 1.

Parents' education level

At each wave, Parent 1 respondents are asked about the highest qualification held by each of the parents. This information is used to categorise parents into those who have a university degree (or higher) and those who don't. Comparisons are made for Parent 1 respondents only, and for both parents together (families in which at least one parent has a university degree, versus families in which neither parent has a university degree).

Parents' employment status

At each wave, Parent 1 reported their employment status as “employed (includes full-time and part-time employment)”, “unemployed” or “not in the labour force”. Jobless family was derived using Parent 1 and Parent 2's employment status. Jobless family refers to two-parent families where both parents were unemployed or not in the labour force, and single-parent families where Parent 1 was unemployed or not in the labour force.

Region of residence

Families' postcodes are used to link to ABS Census data, which identifies whether they live in a metropolitan area (capital city statistical divisions) or non-metropolitan area (the rest of the state outside the capital city statistical divisions).

Neighbourhood disadvantage

Neighbourhood disadvantage was measured using the Socio-Economic Indexes for Areas (SEIFA)—Disadvantage. Those families living in areas in the lowest 25% SEIFA index of disadvantage are considered to be living in an area of socio-economic disadvantage.

1.4 Summary tables

Glossary of LSAC terms

Term Description
B cohort The younger group (“baby” cohort) of study children, aged:
  • 0-1 year in Wave 1 (2004);
  • 2-3 years in Wave 2 (2006);
  • 4-5 years in Wave 3 (2008);
  • 6-7 years in Wave 4 (2010); and
  • 8-9 years in Wave 5 (2012).
K cohort The older group (“kindergarten” cohort) of study children, aged:
  • 4-5 years in Wave 1 (2004);
  • 6-7 years in Wave 2 (2006);
  • 8-9 years in Wave 3 (2008);
  • 10-11 years in Wave 4 (2010); and
  • 12-13 years in Wave 5 (2012).
LSAC Growing Up in Australia: The Longitudinal Study of Australian Children. A nationally representative longitudinal birth cohort study that commenced in 2004. Data are being collected from study children and their parents, carers and teachers, and through linkage with other national datasets.
Parent 1 The child's Parent 1 (P1) is defined as the child's primary caregiver, or the parent who knows the child best, as determined. In the majority of cases, this is the child's biological mother, but is sometimes the father or another guardian.
Parent 2 The child's Parent 2 (P2) lives in the same household as Parent 1 and is usually the partner of Parent 1. In most cases, this is the child's biological father, but can be the mother, another partner of Parent 1 or another guardian.
Parent living elsewhere (PLE)/non-resident parent The child's parent who lives in a different household to Parent 1.
Study child (or child) The sampling unit for LSAC is the study child, so “child” refers to the child selected for inclusion in the study. Data collected and reported relate to this child.
Wave Periods of data collection:
  • Wave 1 in 2004 (B cohort were 0-1 years, K cohort were 4-5 years);
  • Wave 2 in 2006 (B cohort were 2-3 years, K cohort were 6-7 years);
  • Wave 3 in 2008 (B cohort were 4-5 years, K cohort were 8-9 years);
  • Wave 4 in 2010 (B cohort were 6-7 years, K cohort were 10-11 years); and
  • Wave 5 in 2012 (B cohort were 8-9 years, K cohort were 12-13 years).

Statistical indicators in tables and graphs

Indicator Notes
*** Significance level p < .001
** Significance level p < .01
* Significance level p < .05
ns Not statistically significant
I Confidence interval

Key measures used in the report

Scale Range Notes
Index of Community Socio-Educational Advantage (ICSEA) 500-1300 ICSEA is an index of the socio-economic background of the students at the school, with more advantaged schools having a higher ICSEA and schools with students from more disadvantaged backgrounds having a lower ICSEA (Australian Curriculum, Assessment and Reporting Authority [ACARA], 2013). Every school has an ICSEA value on a scale that has a median of 1000 and a standard deviation of 100. ICSEA values range from around 500 (representing extremely educationally disadvantaged backgrounds) to about 1300 (representing schools with students with very educationally advantaged backgrounds) (ACARA, 2013).
Pubertal Development Scale (PDS) 2-8 (girls)
3-12 (boys)
The PDS, developed by Crockett and Petersen in 1987, assesses the pubertal stage based on a number of typical physical indicators of puberty for boys and girls. Parents rate on a 4-point scale ranging from 1 (have not begun) to 4 (development completed). The scores were summed to create puberty category scores to indicate children's pubertal status: pre-pubertal, early pubertal, mid-pubertal, late pubertal and post-pubertal.
Parenting Style Inventory 1-5 The Parenting Style Inventory assesses three dimensions of parenting style: responsiveness, demandingness and autonomy-granting. Children respond to 14 statements regarding the parenting styles of their parents on a 5-point scale (1 = “strongly agree”, 5 = “strongly disagree”). Items were reversely coded and averaged with higher scores indicating higher levels of parental responsiveness, demandingness and autonomy-granting.
Quality of Life (PedsQL) 0-100 Children's emotional functioning, school functioning and peer relationships are measured using the Parent 1-reported Pediatric Quality of Life (PedsQL) inventory (Varni, Burwinkle, & Seid, 2006). Emotional Functioning (five items) assesses the frequency that the child displays negative emotional states such as sadness and anxiety. School Functioning (five items) measures children's school adjustment and performances. Social functioning (five items) assesses children's relationship with their peers. Parents rate each item on a five-point scale, ranging from 1 (Never) to 5 (Almost always). Items are reverse-scored and transformed to a 0 to 100 scale (1 = 100, 2 = 75, 3 = 50, 4 = 25, 5 = 0), so that higher scores indicate a higher level of functioning. Average scores were then calculated for the emotional, school and social functioning subscales.
National Assessment Program - Literacy and Numeracy (NAPLAN) 0-1000 The NAPLAN is designed to assess all Australian students in Years 3, 5, 7 and 9 in reading, writing, language conventions (spelling, grammar and punctuation) and numeracy, using a national test that has been conducted annually since 2008, on the same days each year. The NAPLAN assessment process is performed using a national common reporting format by the test administration authorities. The reporting scales are constructed so that given scale scores can be compared across school year levels and over time.

1.5 References

Australian Bureau of Statistics. (2005). Australian Standard Classification of Languages (ASCL). Canberra: ABS.

Australian Institute of Family Studies. (2011). The Longitudinal Study of Australian Children annual statistical report 2010. Melbourne: AIFS.

Australian Curriculum, Assessment and Reporting Authority. (2013). Report on the generation of the 2012 Index of Community Socio-educational Advantage (ICSEA) (My School Technical Report). Sydney: ACARA. Retrieved from <www.acara.edu.au/verve/_resources/ICSEA_2012_Generation_Report.pdf>.

Blakemore, T., Strazdins, L., & Gibbings, J. (2009). Measuring family socioeconomic position. Australian Social Policy, 8, 121-168.

Cole, T. J., Bellizzi, M. C., Flegal, K. M., & Dietz, W. H. (2000). Establishing a standard definition for child overweight and obesity worldwide: International survey. British Medical Journal, 320, 1240-1243.

Cole, T. J., Flegal, K. M., Nicholls, D., & Jackson, A. A. (2007). Body mass index cut offs to define thinness in children and adolescents: International survey. British Medical Journal, 335(7612), 194.

Cusack, B., & Defina, R. (2014). Wave 5 weighting & non response (Technical Paper No. 10). Melbourne: Australian Institute of Family Studies.

Daraganova, G., & Sipthorp, M. (2011). Wave 4 weights (Technical Paper No. 9). Melbourne: Australian Institute of Family Studies.

Misson, S., & Sipthorp, M. (2007). Wave 2 weighting and non-response (Technical Paper No. 5). Melbourne: Australian Institute of Family Studies.

Sipthorp, M., & Misson, S. (2009). Wave 3 weighting and non-response (Technical Paper No. 6). Melbourne: Australian Institute of Family Studies.

Soloff, C., Lawrence, D., & Johnstone, R. (2005). LSAC sample design (Technical Paper No. 1). Melbourne: Australian Institute of Family Studies.

Soloff, C., Lawrence, D., Misson, S., & Johnstone, R. (2006). Wave 1 weighting and non-response. Melbourne: Australian Institute of Family Studies.

Varni, J. W., Burwinkle, T. M., & Seid, M. (2006). The PedsQLTM 4.0 as a school population health measure: Feasibility, reliability, and validity. Quality of life research, 15(2), 203-215.

Footnotes

1 The terms “Parent 1” and “Parent 2” are used for consistency and are not intended to suggest that one parent's relationship with their child is more important than the other parent's relationship.

2 For separated families in which both parents provided care for the child, the interviewer in Wave 1 worked with the family to identify who the child's Parent 1 was for the purposes of data collection. Where possible, the same parent has been kept as P1 in subsequent waves.

3 See Soloff, Lawrence, and Johnstone (2005) for more information about the study design.

4 Study child's birth weight and length were recorded.

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