Annual Report 2006‚Äď2007

Wave 2 data collection

Fieldwork

The main Wave 2 fieldwork began in April 2006 and was completed in early 2007.

There was very positive feedback from both interviewers and respondents regarding their involvement with the study. As one parent said, "Being part of a study that will be taken into consideration when future services for families are planned is a good feeling"; and from an interviewer, "I would just like to say how thankful I am for having the opportunity to work on Growing Up in Australia. This would have to be the most enjoyable interviewing yet".

Most of the interviews followed the standard procedure of a face-to-face interview in English with the child's primary caregiver. The exceptions were:

The time spent by interviewers in the home was reduced from the Wave 1 average of two hours to one and a quarter hours for Wave 2. The average time for the B cohort (children aged 2-3 years in Wave 2) was 66 minutes, compared with 85 minutes for the K cohort (children aged 6-7 years in Wave 2).

A Freecall Growing Up in Australia 1800 number is available to respondents at all times.

Figure 1 - Interview sample size, Waves 1 and 2

Figure 1

Overall response

In Wave 1, 10,090 families agreed to take part in Growing Up in Australia. Before Wave 2 commenced, 130 of these families had withdrawn from the study. Of the eligible families at Wave 2 (n = 9,960), 9,070 families were interviewed. This represents a response rate of 91.1 per cent of eligible families, and 89.9 per cent of the originally recruited sample. The response rate was similar for both cohorts, with families of 4,606 B cohort children and 4,464 K cohort children being interviewed.

There were 284 refusals at Wave 2 (2.8 per cent of the available sample). These included 80 permanent opt-outs, plus 204 families who refused an interview at Wave 2 but agreed to remain in the study for future waves. Many of the refusals for this wave only were attributed to situational factors, such as being too busy (32 per cent) or having an illness or other family problem (25 per cent). No reason was given in 17 per cent of cases. Among those who permanently withdrew, the most common reasons given were: not interested (16 per cent), too busy (15 per cent) and privacy/inappropriate questions (14 per cent), with 28 per cent not providing any reason at all.

There were 61 families (0.6 per cent) who were away for the entire fieldwork period, and five children had died. A total of 540 families (5.4 per cent) were not able to be located, despite extensive efforts by interviewers and ABS office staff. These families are still considered to be study members. Medicare Australia address updates are being used to help locate these currently non-contactable families.

As noted, only 80 families permanently withdrew from the study during Wave 2. Therefore, the sample size at the end of Wave 2 has been reduced to 9,875 children (5,001 B and 4,874 K), which constitutes 97.9 per cent of the originally recruited cohort.

Characteristics of non-participating families

Non-response analysis showed considerable similarities between the profiles of families who did not respond in Wave 2 and families who declined to take part in the study at Wave 1 (using Australian Bureau of Statistics Population Census data for comparable populations). The Wave 2 non-responding families were also similar to the Wave 1.5 non-responding families. Non-response rates were higher among Indigenous families (20 per cent), single-parent families (19 per cent), families where parents spoke a language other than English at home (15 per cent), and families in which parents had not completed Year 12 at school (13 per cent).

Differences between the response rates for these groups and the total sample were largely due to an inability to locate respondents, rather than significant differences in agreement to participate, and presumably reflect greater mobility, lower-quality contact information and greater difficulty in locating these families.

Rates of questionnaire returns

As in Wave 1, questionnaire responses were sought from the parent or parents who lived with the child, parents living apart from the child, child carers and teachers (as applicable) The final self-complete response rate (showing the percentage of children for whom these forms were applicable) is shown in Table 1. The table also shows the return rate of time-use diaries completed by parents about the child's activities during two specified 24-hour periods.

Table 1 - Self-complete forms response rates

  Response rate %   Response rate %
Parent 1 during interview
98
Time-use diary
76
Parent 1 leave behind
78
Centre-based carer (B cohort)
68
Parent 2
77
Home-based carer (B cohort)
67
Parent living elsewhere
29
Teacher (K cohort)
82

In cases where a child's parent was living apart from the child but saw the child at least annually (1,011 children), about 70 per cent of resident parents provided contact information for the parent living elsewhere. However, only 295 (42 per cent) of parents living elsewhere returned a form.

Almost all parents provided consent to contact either the child's teacher (99 per cent) or carer (97 per cent). The most common reasons for not providing contact information for carers were language issues (25 of the 73 cases) and concern about disturbing the carer (20 cases).

Age of children at time of interview

Table 2 shows the age distribution of the children when their families were interviewed at Waves 1 and 2.

Mainly due to a later start in fieldwork for Wave 2 compared with Wave 1, there was an increase of slightly more than two years in the mean ages between Waves 1 and 2. This difference is not identical for all children, as there was some variation in the time of year that families were interviewed. Fieldwork requirements, and also the time taken to locate non-contactable families, meant that it was impossible to ensure that the time period between waves was the same for all children.

Table 2 - Age distribution of children at time of Wave 1 and 2 interviews

B cohort K cohort
Wave 1 Wave 2 Wave 1 Wave 2
Age % Age % Age % Age %
3-5 months
11.2
2 years 3 months - 2 years 5 months
6.3
4 years 3 months - 4 years 5 months
10.6
6 years 3 months - 6 years 5 months
7.1
6-11 months
73.2
2 years 6 months - 2 years 11 months
64.8
4 years 6 months - 4 years 11 months
72.1
6 years 6 months - 6 years 11 months
63.7
1 year - 1 year 2 months
14.7
3 years - 3 years 2 months
23.5
5 years - 5 years 2 months
16.1
7 years - 7 years 2 months
23.8
1 year 3 months - 1 year 7 months
1.0
3 years 3 months - 3 years 10 months
5.4
5 years 3 months - 5 years 7 months
1.3
7 years 3 months - 7 years 10 months
5.4
Mean SD Mean SD Mean SD Mean SD
9 months 3 months 2 years 10 months 3 months 4 years 9 months 3 months 6 years 10 months 3 months

Final Wave 2 sample characteristics

Table 3 provides a summary of selected characteristics of the Wave 2 sample. To assist in the assessment of the representativeness of the sample, comparative population data from the ABS 2001 Census of Population and Housing have also been provided.

For almost all characteristics, the sample distribution was only marginally different to the Census distribution. The most substantive difference between the sample and Census children was in the educational status of the parents, with proportions for children with mothers who had completed Year 12 being 10 per cent higher for the Growing Up sample than for the Census.

Other differences were: children in lone-parent families were under-represented, more so for the K cohort; children with two or more siblings were under-represented and "only" children were over-represented in the B cohort; children whose mothers speak a language other than English at home were under-represented; children from families with lower incomes were under-represented; and children in New South Wales were under-represented.

Table 3 - Proportion of children in families with given characteristics

Wave 2 characteristics B cohort K cohort
Wave 1 Wave 2 Wave 1 Wave 2
LSAC ABS LSAC ABS LSAC ABS LSAC ABS
% % % % % % % %
Gender*
Male 51.2 51.3 51.1 51.3 50.9 51.3 51.0 51.3
Female 48.8 48.7 48.9 48.7 49.1 48.7 49.0 48.7
Family type
Two resident parents/guardians: 90.7 88.1 89.0 84.0 86.0 82.0 85.2 80.5
- both biological 90.1 na 88.0 na 82.9 na 81.3 na
- step or blended family 0.4 na 0.8 na 2.7 na 3.3 na
- other 0.3 na 0.2 na 0.5 na 0.6 na
One resident parent/guardian: 9.3 11.9 11.0 16.0 14.0 18.0 14.8 19.5
- biological 9.3 na 10.9 na 13.9 na 14.7 na
- other 0.1 na 0.1 na 0.1 na 0.1 na
Siblings
Only child 39.5 36.2 19.3 22.9 11.5 12.1 9.1 9.6
One sibling 36.8 35.6 49.1 43.6 48.4 45.9 45.2 42.4
Two or more siblings 23.7 28.2 31.6 33.5 40.1 42.0 45.7 48.0
Ethnicity
Aboriginal or Torres Strait Islander 4.5 3.5 3.9 4.4 3.8 3.5 3.4 4.4
Mother speaks a language other than English at home 14.5 16.8 13.4 17.5 15.7 17.6 14.7 17.1
Work status
Both parents or lone parent work 47.9 nc 56.9 nc 55.5 nc 65.4 nc
One parent works (in couple family) 40.8 nc 33.8 nc 32.8 nc 26.1 nc
No parent works 11.3 nc 9.3 nc 11.6 nc 8.6 nc
Educational status
Mother completed Year 12 66.9 56.6 69.0 52.0 58.6 48.3 60.1 45.0
Father completed Year 12 58.5 50.2 59.7 47.4 52.7 45.3 53.2 43.1
State*
New South Wales 31.6 34.1 31.1 33.4 31.6 33.7 31.4 33.6
Victoria 24.5 24.6 24.3 24.5 25.0 23.8 23.8 23.9
Queensland 20.6 19.3 21.5 19.8 19.8 19.7 20.6 20.1
South Australia 6.8 6.8 6.7 7.1 6.8 7.2 6.9 7.1
Western Australia 10.4 9.9 10.6 9.8 10.2 10.1 10.6 10.0
Tasmania 2.2 2.3 2.3 2.4 2.7 2.5 2.9 2.4
Northern Territory 1.7 1.4 1.4 1.4 1.7 1.6 1.5 1.3
Australian Capital Territory 2.1 1.7 2.3 1.6 2.3 1.3 2.3 1.6
Region
Capital city statistical division 62.5 63.7 61.9 62.7 62.1 62.1 61.6 61.4
Balance of state 37.5 36.3 38.1 37.3 37.9 37.9 38.4 38.6
Number of families 5,107   4,606   4,983   4,464  

Note: ABS = 2001 census counts for children in families with 0, 2, 4 and 6 year olds, except for those marked *, which are based on September 2004 estimated resident population data for children aged 0, 2, 4 and 6 years.
na = not available; nc = comparable data not available from the census

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