Annual Report 2004

What is Growing Up in Australia?

Growing Up in Australia is the Longitudinal Study of Australian Children (also known as LSAC). This study aims to examine the impact of Australia's unique social, economic and cultural environment on children growing up in today's world. It will further our understanding of early childhood development, inform social policy debate, and be used to identify opportunities for early intervention and prevention strategies in policy areas concerning children.

During 2004, over 10,000 children and their families were recruited to the study from a sample selected from the Health Insurance Commission's Medicare database. It is intended that these children and their families will be followed at two-yearly intervals until 2010, and possibly beyond.

LSAC addresses a range of key research questions about children's development and wellbeing. Information is collected on the children's physical health and social, cognitive and emotional development, as well as on their child care, education, and family and social environment. Respondents include parents, child carers, preschool and school teachers and, in time, the children themselves. The study's longitudinal design will enable researchers to determine optimal periods for the provision of services and welfare support and identify the long-term consequences of policy innovations (see LSAC Discussion Paper No. 1, "Introducing the Longitudinal Study of Australian Children").

LSAC delivers the first-ever comprehensive Australian national data on children as they grow up.

Who is involved?

LSAC was initiated and is funded by the Australian Government Department of Family and Community Services (FaCS) as part of the Government's Stronger Families and Communities Strategy. Responsibility for the design and management of the study rests with the Australian Institute of Family Studies, in collaboration with a consortium of eight other leading research organisations across Australia.

Six Design Teams, as well as a Sampling Design Team, have been formed around the research domains of health, education, child care, family functioning, child functioning and socio-demographics. Each team comprises members from the Consortium Advisory Group as well as others who have expertise in the area. In addition, a Scientific and Policy Advisory Group has been established, comprising international experts on children's development.

The Institute sub-contracted the first wave of data collection to Colmar-Brunton Social Research and I-view, private social and market research companies. Future waves of data collection will be undertaken by the Australian Bureau of Statistics.

Timelines

Development work for the study commenced in March 2002, with the testing phase continuing through 2003. The first phase of the study involving more than 500 families occurred in late 2003. The main phase of recruitment, of over 10,000 children and their families, took place from March until November 2004. A "between-waves" questionnaire will be mailed to all families in the main wave in May-July 2005, prior to the second wave of data collection commencing in March 2006.

Reference population

The essential focus of the study is on the early years of children's lives, and therefore "the child" is the sampling unit of interest. The study has adopted a cross-sequential design that follows two cohorts whose ages will overlap as the study progresses. The sample is broadly representative of all Australian children (citizens and permanent residents) in each of two selected age cohorts: children born between March 2003 and February 2004 (infants) and children born between March 1999 and February 2000 (children aged four to five years). Children in some remote parts of Australia were excluded.

Sample selection

With facilitation by FaCS, the Health Insurance Commission (HIC) agreed to select a random sample of children from the Medicare database, the most comprehensive database of Australia's population. Families of the selected children received letters of invitation to take part in the study, sent by HIC. The sample selection process respected parents' privacy and allowed them to opt-out of the study before their details were passed to the data collection agency, I-view.

About 300 postcodes were selected at random across Australia, and then a number of children from each cohort were selected from these. The sample was stratified by state, capital city statistical division/balance of state, and size of the target population in the postcode. The actual number of children selected per postcode depended on which stratum the postcode was in. Overall, about 18,800 families were sent a letter of invitation by HIC.

The sample achieved in each state and territory is shown in the table below. Since the finalisation of this report, ten cases (three infants and seven 4-5 year olds) have been added to the dataset.

Distribution of final LSAC sample across states and territories
State/Territory Infants 4-5 year olds
ACT 105 106
NSW 1,615 1,573
NT 87 82
QLD 1,053 988
SA 347 339
TAS 113 136
VIC 1,251 1,245
WA 533 507
Total 5,104 4,976

Data collection

Once HIC had removed from the sample any families who had opted out of the study, contact names and addresses were passed to I-view, who then sent another letter to families saying when an interviewer would be in their area. About 130 interviewers recruited families and conducted interviews across Australia.

The main data collection for Wave 1 was a face-to-face interview with the parent who knew the child best (Parent 1). In 97 per cent of cases, Parent 1 was the biological mother. The interview included taking direct physical measurements of the child (such as weight) and, for the 4-5 year old children, direct assessments of school readiness and language. Self-complete modules for Parent 1 and Parent 2 (where Parent 2 was the other resident parent/guardian of the study child and/or the partner of Parent 1) were either filled in during the interview or returned later. The interviewer completed some observations about the neighbourhood, family, parent and child.

The data collection phase also included two time-use diaries which were left behind for the parent to complete about what the study child did in two 24-hour periods. In addition, if the parent agreed, a questionnaire was sent to a carer/teacher who cared for the child for at least eight hours a week.

Wave 1 response

The final response to the recruitment of children was 54 per cent of those families who were sent a letter by HIC. The response rate was higher for the infant cohort, with 57 per cent of families agreeing to take part, compared with 50 per cent of families with 4-5 year old children.

The main sources of sample loss were refusals (31 per cent for the infants and 35 per cent for the 4-5 year olds) and non-contacts - people who had moved or for whom only a post office box address was available (10 per cent for the infants and 14 per cent for the 4-5 year olds). The most common reason given for refusing was "not interested/too busy". Interviewers felt that many parents of young children were very time pressured.

Although the response rate is lower than would be preferred, the main issue is whether the sample is representative of the target population. As is shown in the next section, this is the case for most of the characteristics of the sample, and the more significant differences between the target population and the sample have been compensated through differential weighting of the final sample.

The response rates for the other study materials were:

Sample characteristics

Table 1 provides a summary of selected characteristics of the sample. To assist in the assessment of the representativeness of the sample, comparative (previously unpublished) population data from the ABS 2001 Census of Population and Housing has also been provided.

Table 1. Sample characteristics (unweighted data)
  Infant Child
LSAC Census LSAC Census
No. % % No. % %
Gender*
Male 2613 51.2 51.3 2532 50.9 51.3
Female 2491 48.8 48.7 2444 49.1 48.7
Age range of children**
3-5 months / 51-53 months 573 11.2 n.a. 525 10.6 n.a.
6-11 months / 54-59 months 3727 73.0 n.a. 3585 72.1 n.a.
12-14 months / 60-62 months 748 14.7 n.a. 800 16.1 n.a.
15-19 months / 63-67 months 55 1.1 n.a. 65 1.3 n.a.
Family type
Two resident parents/guardians: 4626 90.7 88.2 4281 86.0 82.1
  - both biological 4598 90.1 n.a. 4126 82.9 n.a.
  - step of blended family 10 0.2 n.a. 107 2.2 n.a.
  - other 21 0.4 n.a. 48 1.0 n.a.
One resident parent/guardian: 475 9.3 11.8 695 14.0 17.9
  - biological 472 9.2 n.a. 688 13.8 n.a.
  - other 3 0.1 n.a. 7 0.1 n.a.
Siblings
Only child 2019 39.6 36.3 570 11.5 12.2
One sibling 1873 36.7 35.8 2409 48.4 46.2
Two or more siblings 1212 23.8 27.9 1997 40.1 41.6
Ethnicity
Aboriginal or Torres Strait Islander 227 4.5 3.5 185 3.7 3.5
Mother speaks a language other than English at home 739 14.5 16.8 778 15.6 17.6
Work status**
Both parents or lone parent in work 2414 48.1 n.a. 2729 55.6 n.a.
One parent works (in couple family) 2036 40.5 n.a. 1613 32.8 n.a.
No parent works 573 11.4 n.a. 569 11.6 n.a.
Educational status
Mother completed Year 12 3408 66.9 56.6 2898 58.6 48.3
Father completed Year 12 2654 58.5 50.2 2239 52.7 45.3
Parents' combined income**
Less than $800 per week 1531 31.7 41.2 1359 29.2 40.6
$800-1499 per week 1980 41.0 39.1 1735 37.3 38.6
$1500 or more per week 1321 27.3 19.7 1563 33.6 20.8
State*
New South Wales 1615 31.6 34.8 1573 31.6 33.7
Victoria 1251 24.5 24.1 1245 25.0 23.8
Queensland 1053 20.6 19.1 988 19.9 19.7
South Australia 347 6.8 7.0 339 6.8 7.2
Western Australia 533 10.4 9.6 507 10.2 10.1
Tasmania 113 2.2 2.3 136 2.7 2.5
Northern Territory 87 1.7 1.6 82 1.7 1.6
Australian Capital Territory 105 2.1 1.5 106 2.1 1.3
Region*
Capital City Statistical Division 3192 62.5 65.1 3088 62.1 61.9
Balance of state 1912 37.5 34.9 1888 37.9 38.1
Total 5104     4976    
Note: *Proportions based on the ABS 2003 Estimated Resident Population data for children aged 0 and 4 years. ABS 2001 Population Census data are based on children aged 0 and 4 years at the time of the Census. In both cases, these are different populations from the LSAC target population, but it is expected that the populations could display similar characteristics.
**Sub-totals may not add to totals, due to missing data. n.a. = not available/applicable.

For almost all characteristics, the sample distribution is only marginally different to the Census distribution. The most significant difference between the sample and the Census children is in the educational status of the parents, where children with mothers who have completed Year 12 are over-represented in the sample, with proportions 10 per cent higher for the sample than for the Census. Other differences are:

Data release

A full set of data, including survey weights, has been prepared for release. Details on accessing the Wave 1 data are given in the section "The public use file".

Looking ahead to Wave 2

LSAC aims to retain all families recruited in Wave 1 for future waves of the study. As the child is the sampling unit of interest, it will be the child who is followed over the years. Specific procedures will be put in place for children where there is a change in the person who knows the child best (Parent 1).

A number of strategies are in place to maintain contact with the children and their families. These include obtaining several types of contact information for both parents, giving families a change of address card and mementos that have details of the 1800 contact number, sending birthday and season's greetings cards to the children, sending annual newsletters updating them on the progress of the study, and maintaining a respondent website.

In addition, about one year after the Wave 1 interview, families are being sent a short "between-waves" questionnaire that they are encouraged to return. For the infant cohort, additional questions have been included on parental working conditions and leave around the time of the birth of the study child, as part of a nested study by Dr Gillian Whitehouse, University of Queensland.

Development of the Wave 2 data instruments is currently underway. The main differences between Wave 1 and Wave 2 are that all child functioning measures will be updated to be age-appropriate and the older cohort will contain considerable information relating to the child's early years at school. In addition, some other new information will be included, such as family of origin measures, a more comprehensive examination of factors influencing obesity, and more detail on what families do together.

 

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