Australian experience in developing disability questions for the census

All topics must:be of major national importance and relevant to usershave a demonstrated need for data for small geographic areas or small population groupsbe suitable for collection via census methodology

Inclusion of a topic in the Australian census

Very high level of demand. (More submissions to the 2001 planning round than for any other item!)

No other source for small area/population data on disability

Information important for allocation of funds for service delivery

Census includes coverage of remote and sparsely settled geographic areas

Demand for disability items in the census

Aim of census disability questions

The aim of the development of census disability questions was to produce a disability measure that was:

reliable able to be included in self-enumeration forms and comparable to the disability survey measure of disability

1976 census included questions on disability

– but data found to be unreliable1996 census

attempted to develop a disability item– but too unreliable to include– an improvement over 1976 measure

2001 census further attempts to develop satisfactory questions

– again too unreliable– again significant improvement over previous measures– identified new approach for any further development

History

A test/retest methodology was used with the census questions followed up 2 weeks later by personal interviews using the disability survey screening questions Results of the two methods compared to produce estimates of match rates, including false positives and negatives

Key assumption The disability survey measure was assumed to be the "true" measure, however

– disability is subjective– this may be a very bold assumption!

Method of testing

The quality standards set before the tests were:1. 80% matched positives on census and survey results2. Close relationship between census and survey disability rates3. Consistent census to survey ratio of disability rates for small population groups and areaswith criterion 1 and 2 needing to be met as a minimum

Quality standards for census disability questions

1 Mark YES or NO for each of the following:Does the person have difficulty:

doing everyday activities such as eating, showering or dressing?

hearing?learning, understanding or remembering things?reading or seeing even with glasses?walking, kneeling or climbing stairs?living independently?doing any other things people of the same age usually do (for eample working, studying, etc.)

Yes No

2 What causes the difficulty shown in Q1 for the person?

Short-term health condition lasting less than six months

Long-term health condition Disability Age Difficulty with English language Other cause - please specify No difficulty

September 1998 test of two types of questionsForm type 4, Yes/No response

Form type 5, scaled responseQ1 How much difficulty does the person have in: (same list as Form type 4)Responses: None, A little, A lot

Form type 4 (yes/no response)

Form type 5 (scaled response)

Census disability rate 15.0% 22.4%

Survey disability rate 19.9% 21.7%

Census to Survey Ratio (census disability population divided by the survey disability population)

0.8 1.0

Matched disability rate (matched census disability as a proportion of the survey disability population)

52.1% 65.9%

False negative rate (survey disability, census no disability) as a proportion of the survey disability population

47.9% 34.1%

False positive rate (survey no disability, census disability) as a proportion of the census disability population

30.9%

September 1998 testSummary of results

Census test Criterion 1(80% matched positives on census and survey)(a)

Criterion 2 (Close relationship between census and survey disability rates)

Criterion 3 (Consistent census to survey ratio for small population groups and areas)

November 1997 No No No

September 1998—Form type 5

No, 66% match achieved Yes Mostly met

September 1998 test

Summary of results achieved against quality criteria set before the test

Planning for the 2006 censusAt the end of the 2001 test, planned to try to collect a different population in 2006, that is, the severe/profound disability population

Use 'need for assistance' (ICF E) within the activity areas of self-care, mobility and/or communication as the starting point rather than impairment

– more easily identified/reported population (still to be tested)– of direct policy relevance as this population is defined as the target group for key disability service funding and provision

Where to from here?

Alternatively: Reconsider objectives of the disability questions in the census from comparability with the Australian disability survey (SDAC) measure to comparability with other country disability measures Collaborate with others to develop a global measure of disability Use the global measure in the 2006 census if available in time

Note: The relatability of the global measure to the SDAC measure would still need to be assessed. For example, in linking the global measure to the survey measure to produce small area predictors.

Where to from here? (continued)