4715.0 - National Aboriginal and Torres Strait Islander Health Survey, 2018-19 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 11/12/2019   
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This document was added or updated on 26/03/2020.

HEARING DATA


In the 2018-19 National Aboriginal and Torres Strait Islander Health Survey (NATSIHS), information about hearing was collected in two ways:

    • reported by the respondent
    • measured using a voluntary hearing test.

REPORTED HEARING IMPAIRMENT

Respondents were presented with a prompt card and asked whether they had any hearing problems that had lasted, or were expected to last, for at least six months.

Respondents who indicated that they had one or more of the following were considered to have long-term hearing impairment in one or both ears:
    • total deafness

    • deaf in one ear

    • hearing loss or partially deaf.

MEASURED LEVELS OF HEARING

Measurements of hearing were collected from respondents aged seven years and over who did not have a cochlear implant using a voluntary, self-administered test. This was the first time this data has been collected by the ABS.

Methodology

The ABS worked with the National Acoustics Laboratories, the research division of Hearing Australia, to create a test that respondents could use on the interviewers' laptops out in the field to:
    • detect whether a respondent had a hearing impairment in one or both ears

    • assess a respondent’s level of hearing impairment where there was a hearing impairment..

The hearing test required respondents to listen through headphones to a series of beeps over two audio frequencies (one kilohertz and four kilohertz) and respond to hearing a beep by pressing a key on the laptop. Respondents were given a chance to practice prior to the test being administered.

Respondents who completed the test were given their results on a Measurements Card (available on the Downloads tab). The result for each ear was reported on the card as:
    • pass, or

    • see your GP or health service.

There is variability in the descriptors and ranges used to describe level of hearing impairment both within Australia and internationally. The test categorised the results into the following levels of hearing impairment for each ear, which were based on advice from the National Acoustics Laboratories:
    • no measured hearing impairment — quietest sound that can be heard is 20 decibels or lower
    • mild hearing impairment — quietest sound that can be heard is between more than 20 decibels and 40 decibels
    • moderate hearing impairment — quietest sound that can be heard is between more than 40 decibels and 60 decibels
    • severe or profound hearing impairment — quietest sound that can be heard is more than 60 decibels.

Respondents with a hearing impairment in both ears were classified as having a mild, moderate, or severe or profound impairment based on the ear with the lowest level of impairment. For example, respondents with a mild impairment in one ear and a moderate impairment in the other ear were classified as having a mild hearing impairment.

There are limitations with the hearing test — for example, the test is undertaken in the field with background noises, rather than in a soundproof room. However, a comparison of hearing test results with reported hearing impairment can indicate a respondent may have an undiagnosed or untreated hearing impairment.

Response rates

The hearing test had a relatively high rate of non-response due to its voluntary and potentially sensitive nature.


Response rates for hearing test, by age(a)

Total persons in sample
Hearing test completed

no.
%

Age group (years)
7–9
743
36.1
10–14
1 094
38.8
15–19
790
41.5
20–24
667
54.3
25–29
729
51.3
30–34
765
51.2
35–39
604
49.0
40–44
562
45.9
45–49
615
47.6
50–54
535
47.1
55 years and over
1 673
44.7
Total persons aged 7 years and over
8 777
45.5

(a) Respondents who did not have a cochlear implant.


The data from those who undertook the hearing test was then used to impute the data for those who had not taken part in the test. Imputation gives a more complete and useful dataset. The following information was produced from the hearing test:
    • summary result code for left ear (normal, mild, moderate, severe or profound)
    • summary result code for right ear (normal, mild, moderate, severe or profound)
    • whether hearing issue in one or both ears.

How imputation works

Missing values were imputed using two steps.

Firstly, all persons aged seven years and over were imputed as having a severe or profound hearing impairment in both ears if they reported they:
    • had a cochlear implant
    • had total deafness
    • had a hearing aid in both ears.

Then a 'hot decking' imputation method was used. In this method, a record with a missing response (the 'recipient') receives the response of another similar record (the 'donor'). Due to the low response rates, a donor could be used up to five times to populate recipient records. Persons with imputed values from the first step were excluded from this second step of the imputation process.

After some correlation analysis, a number of characteristics (imputation variables) were used to match recipients to donors:
    • sex
    • whether uses a hearing aid
    • disability status
    • highest year of school completed
    • proficiency in English
    • labour force status
    • state/territory of residence
    • type of health services available in local area.

For example, a female recipient who has a hearing aid in one ear, has a profound disability, has completed Year 10 or higher, speaks English well or very well, is not in the labour force, lives in Tasmania, and has no doctor/GP in the local area will match to a donor record who has the same profile (female, has a hearing aid in one ear, has a profound disability, etc).

Using these variables, all of the eligible recipient records were able to be imputed successfully.

Impact of imputation

The table below shows the impact of imputation on summary results for left and right ears.


Measured and imputed hearing test results(a)

MEASURED ONLY(b)
MEASURED AND IMPUTED(c)


Left ear
Right ear
Left ear
Right ear




Level of hearing impairment
no.
%
no.
%
no.
%
no.
%

No measured hearing impairment
2 455
62.5
2 496
63.5
5 304
60.3
5 435
61.8
Mild hearing impairment
978
24.9
942
24.0
2 191
24.9
2 060
23.4
Moderate hearing impairment
279
7.1
298
7.6
604
6.9
657
7.5
Severe or profound hearing impairment
219
5.6
195
5.0
693
7.9
640
7.3
Total
3 931
100.0
3 931
100.0
8 792
100.0
8 792
100.0

(a) Using 2018–19 National Aboriginal and Torres Strait Islander Health Survey unweighted sample counts.(b) Respondents aged seven years and over with no cochlear implant. (c) Respondents aged seven years and over.


Weighting imputed data

The imputation process meant that a new set of replicate weights had to be created for the imputed hearing test data. This is because the imputation process used donor records (and could use them up to five times), which can artificially lower the Relative Standard Errors. The new set of replicate weights adjusted for this and for the additional uncertainty in the estimates due to the use of imputed values rather than reported values.

Jackknife variance estimation for hot deck imputation was used to create the new replicate weights. This resulted in an increased variance when compared to the un-imputed data, which is to be expected.

Each record also retained the original main weight calculated as part of the normal weighting process — see Response rates, sample counts and estimates (appendix).