2004/5 INDIGENOUS HEALTH SURVEY SAMPLE DESIGN
The 2004/05 Indigenous Health Survey (IHS) is the first in a new series of regular six-yearly Indigenous health surveys which are planned to coincide with every second triennial National Health Survey (NHS). The sample design for the IHS was finalised in late February 2004, and sample selections are currently being considered by Population Survey Operations' regional offices.
The sample design process has been considered an improvement on previous Indigenous household surveys, in particular the recent 2002 Indigenous Social Survey (ISS).
The ISS experience highlighted the many challenges associated with large scale Indigenous surveys with multiple competing objectives. A post enumeration workshop for the ISS was held in March 2003, to identify 'lessons learnt' and possible improvements for IHS development, particularly for sample design. One problem with the IHS was the large screening sample needed, due to the lower than expected identification rate of indigenous households. Initial discussions suggested that a major rethink of indigenous sample design was needed to solve this and other problems. Eventually, the workshop found that the sampling strategy itself was not the main problem, and that improvements to the fundamental inputs used to guide the sample design were needed.
The IHS sample design was largely a refinement of that adopted in ISS. The sample was split into two components; a 'remote' sample which is drawn from a selection of remote discrete Indigenous communities, and a 'non-remote' sample which is selected via a screening process from a selection of census collection districts. The focus for the IHS was on ensuring that the fundamental input parameters to the design were sufficiently formulated. Specific improvements included:
- updating of both the Indigenous community frame for the remote sample and a non-community frame for the screened sample;
- cost model development using detailed cost data captured from the ISS to facilitate decisions on cluster size and person per household choices and the sample allocation process;
- modelling of 'hit rates' from the ISS non-remote sample; and
- a flexible allocation mechanism that enabled a range of allocation scenarios to be assessed in a timely fashion.
The final sample is expected to be more efficient than the ISS, and the management of enumeration is expected to proceed more smoothly. Whilst there was only minimal reduction to the level of screening compared to the ISS, the use of external administrative data sources such as public housing lists and Indigenous health clinic data to facilitate the screening exercise remains a possibility.
For more information please contact Alistair Rogers on (02) 6252 7334, or Email: al.rogers@abs.gov.au