Social Research Centre workshop - Telephone Surveying in the Post-Modern Era, held Thursday 10 October 2019. Presentation by Ben Phillips, Senior Research Director, Survey Methodology (Social Research Centre)

1. A subsidiary of:
Current Status of Landline and Mobile
Coverage
Telephone Interviewing in the Post-Modern Era Conference
Melbourne
10 October 2019

2. www.srcentre.com.au
Author
Dr Benjamin Phillips
Senior Research Director, Survey Methodology, Social Research Centre
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3. www.srcentre.com.au
Acknowledgements
Australian Bureau of Statistics
Findings based on use of ABS microdata: Australian Bureau of Statistics.
2017-18 National Health Survey. Microdata type: Detailed Microdata.
Method of Access: DataLab.
Jack Barton
Analyst, Social Research Centre
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Coverage matters
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Coverage
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Population of interest
Sampling frameOver-coverage
Under-coverage
Coverage

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Coverage error
Coverage error:
𝑌𝐶 − 𝑌 =
𝑈
𝑁
× 𝑌𝐶 − 𝑌𝑈
where
𝑌𝐶 = Mean of covered population
𝑌𝑈 = Mean of population not covered
𝑌 = Mean of entire target population
𝑈 = Size of population not covered
𝑁 = Size of target population
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Rate of under-coverage
Difference between
covered and uncovered
units

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Data

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National Health Survey 2017-18
Questions on telephone access and whether phone number was listed
Face-to-face survey with area-probability sample
16,384 households interviewed
Excludes
 Very Remote Australia (0.8% of adults)
 Non-private dwellings (hotels, hospitals, nursing homes, short-stay
caravan parks)
Response rate 76.1%
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Cross-check with ACMA data
Percentage of adults with landline access
 58.0% ACMA
 57.4% NHS
Percentage of adults using mobile phone
(excluding non-telephone households)
 96.0% ACMA
 95.3% NHS
Mobile only
 41.0% ACMA
 40.6% NHS
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



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Phone status

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Adult phone status
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Mobile only
40.6%
Dual-user
52.8%
Landline only
4.6%
No phone
2.0%

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Random digit dialling (RDD)
coverage

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False positive rate
To improve efficiency, SamplePages pre-screens for non-working numbers
(sometimes called ‘pulsing’ or ‘pinging’):
 Signalling System 7 (SS7) for landlines
 Home Location Register (HLR) lookup + some dialling for mobile phones
False negative rate = 1% (working number incorrectly tagged as non-
working)
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Dual-frame RDD coverage
98.0% 99.0% 97.0%
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Telephone
coverage
RDD true
positive
rate*
RDD
coverage
* True positive rate = 1 – false negative rate

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Landline
RDD coverage
57.4% 99.0% 56.8%
Mobile
RDD coverage
93.4% 99.0% 92.5%
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Single frame RDD coverage
Phone
coverage
True
positive
rate
Landline
RDD
coverage
Phone
coverage
True
positive
rate
Mobile
RDD
coverage
Mobile RDD suitable as a stand-alone frame for national general population surveys

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RDD coverage of specific
populations

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Phone status by age group
49%
64%
51%
35%
29%
22%
9%
48%
33%
46%
61%
65%
67%
61%
1% 1% 1%
3% 4%
9%
28%
2% 2% 2% 2% 1% 3% 2%
0%
20%
40%
60%
80%
100%
18-24 25-34 35-44 45-54 55-64 65-74 75+
Mobile only Dual-user Landline only No phone
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* *
* RSE > 25%

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Landline coverage by age group
49%
34%
47%
63%
69%
75%
89%
0%
20%
40%
60%
80%
100%
18-24 25-34 35-44 45-54 55-64 65-74 75+
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Mobile coverage by age group
97% 97% 97% 96% 95%
89%
70%
0%
20%
40%
60%
80%
100%
18-24 25-34 35-44 45-54 55-64 65-74 75+
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Phone status by state
39% 37%
45% 44% 42% 46%
61%
45%
55% 56%
48% 49% 53% 48%
30%
49%
5% 4% 5% 6% 4% 6%
3%
4%
1% 3% 3% 1% 2% 1%
7%
2%
0%
20%
40%
60%
80%
100%
NSW VIC QLD SA WA TAS NT ACT
Mobile only Dual-user Landline only No phone
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*
* RSE > 25%

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Landline coverage by state
60% 60%
53% 55% 56%
54%
32%
53%
0%
20%
40%
60%
80%
100%
NSW VIC QLD SA WA TAS NT ACT
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Mobile coverage by state
94% 93% 93% 93% 95% 93%
91%
94%
0%
20%
40%
60%
80%
100%
NSW VIC QLD SA WA TAS NT ACT
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White Pages sample coverage

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Questions asked
Is [your/his/her] landline number listed in the white pages?
1 Yes
2 No
6 Don’t know
[Is that mobile number/Are any of these mobile numbers] listed in the white
pages?
1 Yes
2 No
6 Don’t know
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White Pages (WP) coverage
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In WP
31.2%
Unknown WP
status
9.3%
Not in WP
57.5%
No phone
2.0%

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Landline
Not in WP,
32.7%
In WP,
50.6%
Unknown,
16.7%
Mobile
Not in WP,
95.4%
In WP,
4.6%
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White Pages coverage by frame

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Correlates
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Phone status by Indigenous status
59%
40%
31%
53%
5%
5%6%
2%
0%
20%
40%
60%
80%
100%
Indigenous Not Indigenous
Mobile only Dual-user Landline only No phone
*
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* RSE > 25%
*

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Phone status by year of arrival
60%
29%
41%
37%
62%
53%
1% 7% 5%
3% 2% 2%
0%
20%
40%
60%
80%
100%
2006-18 Pre-2006 Born in Australia
Mobile only Dual-user Landline only No phone
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*
* RSE > 25%

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Phone status by education
32%
39% 42% 46%
52%
55% 53% 51%
12%
4% 3%
2%
3%
2% 2% 2%
0%
20%
40%
60%
80%
100%
Less than Year 12 Year 12 Cert III/IV, Dip, Adv Dip Bachelor's and above
Mobile only Dual-user Landline only No phone
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Socio-economic indexes for areas (index of relative socio-
economic advantage)
43% 42% 43% 40%
35%
47% 50% 50% 56%
61%
7% 5% 5% 3% 4%
3% 2% 2% 1% 1%
0%
20%
40%
60%
80%
100%
1st (most
disadvantaged)
2nd 3rd 4th 5th (least
disadvantaged)
Mobile only Dual-user Landline only No phone
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Housing tenure (households)
20%
40%
64%
71%
58%
31%
8% 1% 3%
1% 1% 2%
0%
20%
40%
60%
80%
100%
Owner without a mortgage Owner with a mortgage Renter
Mobile only Dual-user Landline only No phone
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Phone status by smoking
51%
37% 40%
43%
56% 54%
4% 5% 5%
3% 2% 2%
0%
20%
40%
60%
80%
100%
Current smoker Ex-smoker Never smoked
Mobile only Dual-user Landline only No phone
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Phone status by lifetime risk from alcohol
46%
40% 40% 37%
49%
56% 52%
50%
2% 3% 6%
10%
2% 2% 2% 3%
0%
20%
40%
60%
80%
100%
Exceeded
guidelines
Did not exceed
guidelines
Last consumed alcohol
1+ week ago
Never consumed
alcohol
Mobile only Dual-user Landline only No phone
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Phone status by short-term risk from alcohol
49%
33% 36% 37%
48%
60% 50% 50%
1% 5%
10% 10%
2% 2% 3% 3%
0%
20%
40%
60%
80%
100%
Exceeded
guidelines
Did not exceed
guidelines
Last consumed alcohol
12+ months ago
Never consumed
alcohol
Mobile only Dual-user Landline only No phone
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Summary

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Summary
Dual-frame RDD has excellent population coverage (97.0%)
Single-frame mobile RDD has good population coverage (92.5%); only falls
below 90% for age 65 and above
 Single-frame mobile RDD now viable for national general population
Landline RDD coverage is low overall (56.8%); below 50% for age 44 and
under; NT especially low (32.1%)
White Pages coverage is very low (31.2% known listed + 9.3% with
unknown listing status)
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38.  PO Box 13328
Law Courts Victoria 8010
 03 9236 8500
A subsidiary of:
38
Thank you
benjamin.phillips@srcentre.com.au