Annual Report 2007–2008
Wave 2.5
Between-wave surveys provide a valuable opportunity to address issues in further depth or breadth than may be possible in the main waves, and to enhance participant engagement and retention. With these objectives in mind, a decision was taken in 2006 to include an additional wave of data collection in the form of a mail-out survey between Waves 2 and 3 of Growing Up in Australia.
The mail-out was conducted by the Australian Bureau of Statistics and took place on 20 August 2007. Questionnaires were posted to the entire retained sample for whom contact information was available (close to 9,600 families). Four weeks after the initial mail-out, all families were sent a thank you/ reminder card, and replacement forms were posted after a further three weeks if families had not returned forms. Finally, approximately 1,000 families who had not returned forms ten weeks after the initial mail out were contacted by phone to seek their participation.
The 8-page forms (slightly different for each cohort) included questions on children's engagement with media and technology, children's developmental progress, their child care experiences, family stressful life events, parents' employment status and work-related issues, and child support arrangements (for separated parents).
Around 6,500 forms were returned, 68% of those who received the mail-out. The response rate was highest for families who had been interviewed in Wave 2 (about 72%), although forms were also received from 20% of families who had not participated in Wave 2.
Sample characteristics
The final sample achieved from Wave 2.5, for analysis purposes, included 3,246 B cohort and 3,252 K cohort children. Table 3 provides a summary of the characteristics of the children and families who responded to Wave 2.5, as well as giving data on the sample distribution at each wave, which provides an indication of the representativeness of the sample.
Table 3 (on page 10) shows that the Wave 2.5 sample differed from the Wave 2 sample in similar ways to which the Wave 1.5 sample differed from the Wave 1 sample. Two-parent families, families in which mothers or fathers had completed Year 12 education, and families in which the study child had a sibling were over-represented in the two between-waves samples for both cohorts. Families of Aboriginal or Torres Strait Islander children and families where the mother spoke a language other than English were under-represented for both cohorts.
These differences should be taken into account when interpreting findings from the Wave 2.5 data.
Table 3: Composition of the sample at each wave, B and K cohorts (percentage)
|
B cohort |
K cohort |
||||||
|---|---|---|---|---|---|---|---|---|
W1 |
W1.5 |
W2 |
W2.5 |
W1 |
W1.5 |
W2 |
W2.5 |
|
Study child gender |
||||||||
Male |
51.2 |
51.8 |
51.1 |
50.9 |
50.9 |
51.4 |
51.0 |
51.0 |
Female |
48.8 |
48.3 |
48.9 |
49.1 |
49.1 |
48.6 |
49.0 |
49.1 |
Family type* |
||||||||
Two resident parents/guardians |
90.7 |
93.5 |
89.0 |
91.9 |
86.0 |
89.3 |
85.2 |
88.8 |
One resident parent/guardian |
9.3 |
6.5 |
11.0 |
8.1 |
14.0 |
10.7 |
14.8 |
11.2 |
Siblings* |
||||||||
Only child |
39.5 |
40.1 |
19.3 |
18.7 |
11.5 |
10.6 |
9.1 |
8.3 |
One sibling |
36.8 |
38.3 |
49.1 |
51.5 |
48.4 |
51.4 |
45.2 |
47.7 |
Two or more siblings |
23.7 |
21.6 |
31.6 |
29.7 |
40.1 |
38.0 |
45.7 |
44.0 |
Ethnicity |
||||||||
Aboriginal or Torres Strait Islander |
4.5 |
2.6 |
3.9 |
2.3 |
3.8 |
2.5 |
3.4 |
2.3 |
Mother speaks a language other than English at home* |
14.5 |
12.4 |
13.4 |
11.0 |
15.7 |
13.9 |
14.7 |
13.2 |
Work status* |
||||||||
Both parents or lone parent work |
47.9 |
51.8 |
56.9 |
59.6 |
55.5 |
59.1 |
65.4 |
69.1 |
One parent works (in couple family) |
40.8 |
40.7 |
33.8 |
34.1 |
32.8 |
32.9 |
26.1 |
25.3 |
No parent works |
11.3 |
7.5 |
9.3 |
6.3 |
11.6 |
8.0 |
8.6 |
5.6 |
Educational status* |
||||||||
Mother completed Year 12 |
66.9 |
73.5 |
69.0 |
74.7 |
58.6 |
63.1 |
60.1 |
64.3 |
Father completed Year 12 |
58.5 |
61.4 |
59.7 |
63.1 |
52.7 |
55.8 |
53.2 |
56.5 |
State |
||||||||
New South Wales |
31.6 |
30.7 |
31.1 |
30.1 |
31.6 |
31.2 |
31.4 |
31.5 |
Victoria |
24.5 |
25.4 |
24.3 |
25.0 |
25.0 |
25.3 |
23.8 |
24.3 |
Queensland |
20.6 |
20.2 |
21.5 |
21.2 |
19.8 |
19.8 |
20.6 |
20.3 |
South Australia |
6.8 |
7.3 |
6.7 |
7.0 |
6.8 |
6.7 |
6.9 |
7.1 |
Western Australia |
10.4 |
10.4 |
10.6 |
10.4 |
10.2 |
10.4 |
10.6 |
10.2 |
Tasmania |
2.2 |
2.3 |
2.3 |
2.5 |
2.7 |
2.9 |
2.9 |
2.9 |
Northern Territory |
1.7 |
1.3 |
1.4 |
1.4 |
1.7 |
1.5 |
1.5 |
1.2 |
Australian Capital Territory |
2.1 |
2.6 |
2.3 |
2.5 |
2.3 |
2.2 |
2.3 |
2.5 |
Region |
||||||||
Capital city statistical division |
62.5 |
63.8 |
61.9 |
61.9 |
62.1 |
62.3 |
61.6 |
62.7 |
Balance of state |
37.5 |
36.2 |
38.1 |
38.1 |
37.9 |
37.7 |
38.4 |
37.3 |
Number of observations |
5,107 |
3,573 |
4,606 |
3,246 |
4,983 |
3,594 |
4,464 |
3,252 |
Note: Where information on a particular sample characteristic was available from the between-wave survey, all families who responded to the between-wave survey were included in the data for that characteristic. However, on characteristics for which data were not available at the between-wave survey (denoted by *), data was provided from the previous main wave. For these characteristics, Wave 2.5 responding families were not included if they did not respond to Wave 2. So, for example, family type indicates the proportion of Wave 2.5 respondents who also responded to Wave 2 and contained two resident parents at the time of interview in Wave 2. Percentages may not total 100% due to rounding.