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Ruth E. Weston
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The Australian Family Panel Survey represents a major research undertaking by the Australian Institute of Family Studies that will help the Institute meet its principal task of identifying and understanding factors affecting the stability of Australian families. This paper outlines some of the design proposals that have been developed.
An earlier Institute Briefing Paper explained the rationale behind the development of the panel survey (Saunders and Glezer 1999). This paper outlines some of the design proposals that have been developed. The Institute is interested in obtaining feedback on these matters from other people.
Panel designs involve the collection of the same data on the same group of people on more than one occasion. They enable an examination of the level of stability or change in objective circumstances, behaviour, interpersonal relationships, and the subjective world of individuals. They help us to distinguish between outcomes and their causes by revealing the temporal order of variables. Thus, panel studies enable an estimation of the probabilities of certain personal or family trajectories taking place.
Panel surveys are also extremely valuable tools for assessing the impact of various changes in policy, such as the extent to which changes to youth payments affect the morale, aspirations, family life, and employment opportunities of young people. In addition, panel surveys that are based on large, representative samples of the community and that gather a broad range of policy relevant information are ideally suited for research into social issues as they emerge.
While the repeated collection of the same data from the same individuals represents the essential ingredient of a panel design, each wave in the panel survey can also be used to collect new information for additional 'bolt on' research. Data from previous waves provide a wealth of background information for such studies.
Aims of the survey
The Institute's Australian Family Panel Survey is being designed to achieve the following aims:
There are three basic types of panel surveys: rotating surveys, non-rotating
surveys, and cohort studies. Non-rotating panel surveys have an indefinite
life and follow up a single sample (although various strategies may be
adopted to add to this sample over time). Rotating panel surveys follow up
more than one sample for a restricted period, with the first wave for each
sample being staggered. Thus one sample 'drops out' (temporarily or
permanently), while another begins or continues. Cohort studies focus on
population sub-groups that have experienced a certain event in a given
period - for example, birth cohort, marriage cohort, divorce cohort.
Each of these approaches has advantages and disadvantages (Buck, Ermisch
and Jenkins 1996; Commonwealth Department of Family and Community
Services 1999; Duncan and Kalton 1987). The most suitable approach for any
survey depends on the purposes of that survey and the key research
questions that will be asked.
The Institute's survey will be an indefinite life panel with interviews at fixed intervals with no rotation, but with some built-in self-replacement strategy. This approach is consistent with several panel surveys conducted in other countries - for example, the British Household Panel Study, the US Panel Study of Income Dynamics, the German Socio-Economic Panel survey, and the European Community Housing Panel survey.
Interviews will be conducted every two years. A tracking exercise will be undertaken 12 months after each wave to maintain contact and update information about the whereabouts and basic socio-demographic circumstances of those in the sample.
People who are highly transient (for instance, young people who live for a
few weeks with their parents then move in with friends for a while, before
changing residence again) tend to be under-represented in survey samples.
Furthermore, transient people who happen to be included in the first wave
of a longitudinal study would be very difficult to locate in subsequent waves.
Questions will therefore be included in the survey to identify transient
members of households. The Institute welcomes any suggestions regarding
this matter.
The core elements in the questionnaire will include:
Where possible, the panel survey will complement other relevant Australian studies, including the forthcoming Household, Income and Labour Dynamics Survey planned by the Commonwealth Department of Family and Community Services, and the Negotiating the Life Course Survey run by the Australian National University.
The sample and mode of data collection
Ideally, the Australian Family Panel Survey would be based on a representative sample of all households in Australia. However, most, if not all, data collection will rely on the Institute's Computer-Assisted Telephone Interviews (CATI). The CATI system enables cost-effective, detailed surveys to be undertaken in-house and quickly. High quality data are derived through the computerised checks for inconsistencies in responses, the combining of interviewing with data entry, and ready supervision of interviewers (Mills 1994).
Thus, the practicalities are such that the study is likely to be restricted to
households with telephones - possibly only those with listed numbers. In
September 1996, around 97 per cent of households in Australia had a
telephone (Bennett and Steel forthcoming). Those without a telephone
include disproportionate numbers of people living in rented
accommodation, the unemployed, young low income families, newly
arrived migrants, families headed by mothers, single-person households,
and households located outside capital cities (Steel, Vella and Harrington
1996; Trewin and Lee 1988). Weighting procedures will be used to
compensate for the various types of biases linked with sample derivation.
Over-sampling?
Over-sampling enables the achievement of adequate numbers of certain households - especially uncommon households - for cross-sectional analysis (such as sole father families, stepmother families). However, over-sampling is expensive because it takes numerous telephone calls to locate uncommon households, unless the over-sampling is based on regional location and hence telephone prefix. Second, the data would also need to be weighted to compensate for over-sampling. A simple random sample of telephone numbers will therefore be used.
Stratification
Stratified sampling produces a more representative (and thus more accurate)
sample than simple random sampling. This is because stratified sampling
ensures that the relative proportions of particular groups of interest
represented in the sample are the same as for the population (de Vaus 1995).
While this increased representativeness comes at the cost of a more
complicated sampling design, the gains are usually worth it.
The Australian Family Panel Survey will be stratified according to geographical location. Table 1 sets out the likely number of households to be selected in each State of Territory for a sample of around 5000 households.
| Table 1. Estimated number of households in the Australian Family Panel Survey by State and Territory* | |
|---|---|
| State/Territory | Number |
| New South Wales | 1670 |
| Victoria | 1230 |
| Queensland | 930 |
| Western Australia | 500 |
| South Australia | 410 |
| Tasmania | 130 |
| Australian Capital Territory | 80 |
| Northern Territory | 50 |
| Total | 5000 |
| *Plus or minus ten households. | |
| Source: Based on data from the Australian Bureau of Statistics, 1999. | |
Non-response is an unavoidable problem arising from failures to contact, refusals, and a contacted individual's inability to participate owing to physical or mental disability or language barrier.
Response rates vary according to the nature of the population from which the sample is selected. Elderly people and those with low education are less inclined to participate in surveys than younger people and the better educated (Groves and Lyberg 1988).
Telephone surveys result in lower response rates compared with face-to-face interviews. In addition, respondents are more likely to terminate the interview prematurely if interviewed by telephone rather than face-to-face (Groves and Lyberg 1988).
British experience suggests that the refusal rate for a 40-minute telephone interview will be around 5 per cent higher than that involving a 20-minute telephone interview (Groves and Lyberg 1988).
However, the Institute's primary concern is not simply to maximise survey response in the first wave of the survey, but also to maximise sample retention across all subsequent waves. This poses some difficulties, as aggressive efforts to boost the response rate in Wave 1 may fail to engage respondent cooperation and consequently result in a lower than otherwise retention rate in subsequent waves. Also, non-response needs to be managed at two levels, initially that of the first household contact, and subsequent contact with each selected person within the household.
Response rates for Institute surveys conducted via CATI have varied from 57 to
87 per cent or 40 to 77 per cent, depending on the calculation method adopted.
However, none of these surveys is directly comparable to the panel survey.
Why select households and not families?
The short answer to the question of why households and not families are to
be selected is that families extend beyond households. More formally,
however, the Australian Bureau of Statistics defines a family as 'two or more
persons, one of whom is at least 15 years of age, who are related by blood,
marriage (registered or de facto), adoption, step or fostering, and who are
usually resident in the same household' (ABS 1997: 48). This means that a
household can contain more than one family, but a family is not spread
beyond a single household. That is, the notion of family is restricted to a unit
or units within a household.
In reality, however, families are more diffuse than this. People living alone and
'unrelated' people living in 'group households' have families with whom they
are not living. Children who have left home - either temporarily or
permanently - are likely to be seen as 'family' to their parents and vice versa. In
addition, most children of divorced families see their non-resident father (along
with any resident step-parent) as part of their family (Funder 1991).
Therefore, as most people see families as extending beyond households, it
makes sense to target households and then ask household members about
their families.
Sample size and unit of analysis
The unit of analysis will be the individual person rather than family or household. That is, individuals who remain in the household and those who move out will be tracked.
A sample of 5000 households will be selected. Attempts will be made to
interview all adult members of the household. In addition, the pilot study
will seek parental permission for interviews with children aged 12 years and
upward. The results of this study will determine the age cut-off for interview
in Wave 1.
Information about younger children will be sought from a parent - in most
cases, the mother.
Who will be followed over the course of the panel?
Rules for identifying household members who will be followed up -
'following rules' - are being developed. For example:
'Bolt-on' studies may involve the addition of new samples (to increase the numbers in subgroups of interest). This would be undertaken after consultation with the sampling consultant.
Maintaining a representative sample
A key problem with indefinite life panel surveys is the fact that the sample becomes progressively less representative of the population, for two reasons. First, it does not include newcomers to the population. Second, there are likely to be systematic differences between those who drop out of the survey and those who continue - for example, young people and those who divorce are more likely to be mobile and thus difficult to trace.
No decision has yet been made about whether or not immigrants should be added to the sample.
Regarding attrition, a system will be set in place to promote and maintain the interest of respondents without harassing them. Details of this system will form part of a published Australian Family Panel Survey document.
Immediate steps and longer term outcomes
The Australian Family Panel Survey will provide rich details about interpersonal relationships between family members within the household and across household boundaries. It will also enable the tracking of the personal trajectories of individual sample members (including young children not interviewed) and the identification of factors contributing to these trajectories. A pilot study will be undertaken in May/June 2000. Wave 1 will begin in Spring 2000.
The feasibility of continuing with the study will depend on response rates. This will be monitored closely, as will the reliability and validity of the questions asked.
References
ABS (1997), Family Characteristics, Australian Bureau of Statistics, Catalogue No. 4442.0.
ABS (1999), Household and Family Projections, Australia: 1996 to 2021, Australian Bureau of Statistics, Catalogue No. 3236.0.
Bennett, D.J. & and Steel, D. (forthcoming), 'An evaluation of a large scale
CATI household survey using random digit dialling', Australian & New
Zealand Journal of Statistics.
Buck, N., Ermisch, J., & Jenkins, S.P. (1996), Choosing a longitudinal survey
design: the issues. Colchester [Eng.] : ESRC Research Centre on Micro-Social
Change, University of Essex, c1996
Commonwealth Department of Family and Community Services (1999), Household, income and labour dynamics in Australia (HILDA) survey: Draft Proposed Implementation Plan. September. Strategic Policy and Analysis Branch, Research Strategies Section.
de Vaus, D. (1995), Surveys in social research (fourth edition). Allen & Unwin, St. Leonards, NSW.
Duncan, G.J., & Kalton, G. (1987), 'Issues of design and anlaysis of surveys across time'. International Statistical Review, Vol. 55, No. 1, pp. 97-117.
Funder, K. (1991), 'Children's constructions of their post-divorce families: a family sculpture approach', in K. Funder (ed.), Images of Australian Families, Longman, Melbourne.
Groves, R.M. & Lyberg, L.E. (1988), 'An overview of non-response issues in telephone interview', in R.M. Groves, P.P. Biemer, L.E. Lyberg, J.T. Massey, W.L. Nicholls, & J. Waksberg (eds) Telephone Survey Methodology, Wiley, New York.
Mills, E. (1994), 'Telephone interviewing at the Institute', Family Matters no.
39, pp. 32-33.
Saunders, P. (1999), Australian Institute of Family Studies: Research Plan
1999-2001. Australian Institute of Family Studies, Melbourne.
Saunders, P. & Glezer, H. (1999), The New Australian Family Panel Survey, Australian Family Briefing No. 7, Australian Institute of Family Studies, Melbourne.
Steel, D., Vella, J. and Harrington, P. (1996), 'Quality issues in telephone surveys: coverage, non-response and quota sampling', The Australian Journal of Statistics, vol. 38, pp. 15-34.
Trewin, D. & Lee, G. (1988), International comparisons of telephone coverage', in R.M. Groves, P.P. Biemer, L.E. Lyberg, J.T. Massey, W.L. Nicholls & J. Waksberg (eds) Telephone Survey Methodology, Wiley, New York.
© Australian Institute of Family Studies - Commonwealth of Australia 2000
The panel survey will form part of the responsibilities of the Australian Institute of Family Studies new Research Operations Unit. The team includes:
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