Population data collection:

a government perspective

Dr Sarah Joyce

Manager Health Survey Unit

WA Department of Health

Outline

Importance of population data collection

WA Health and Wellbeing Surveillance System

(HWSS)

Aims and objectives

Methodology

Challenges in data collection and analysis

Mortality & Morbidity People with problems

not requiring hospitalisation

Healthy people

People ‘at risk’ but problem-free

Administrative datasets

e.g. hospitalisations,

deaths, cancer registry

Population based

surveys e.g. Health and

Wellbeing Surveillance

System

Importance of population

data collections

Whole

population

Health and Wellbeing

Surveillance System

(HWSS)

Population based survey run continuously since 2002

Used to inform and evaluate programs, inform and

support policy development, health service planning and

development

Adult and child reports available annually

Data used for Departmental performance indicators,

national reporting and specific requests

HWSS

Lifestyle

risk factors

Smoking Physical

activity

Alcohol

Sun protection

Nutrition

Sleep

Health Service Utilisation

Physiological

risk factors

Body weight

Cholesterol

Blood

pressure

Chronic

Conditions

Cancer

Mental health

Asthma

Osteoporosis

Heart Stroke

Injury

Arthritis Respiratory

Child

Development

Breastfeeding

Speech

Birth weight

School

Bullying Sociodemographics

Income Employment

Living

arrangements

Family

structure

Education

Welfare Mental

wellbeing

Kessler

Major life events

SF8

Social

support

Suicide

Population based survey run continuously since 2002

Used to inform and evaluate programs, inform and

support policy development, health service planning and

development

Adult and child reports available annually

Data used for Departmental performance indicators,

national reporting and specific requests

Health and Wellbeing

Surveillance System

(HWSS)

HWSS – Aims and

objectives

Monitor the health and wellbeing of Western Australians

Identify health status and lifestyle behaviours

Identify emerging issues in a timely manner

To provide information at health region level, and where

possible at smaller geographic levels

To provide information about trends over time as well as

seasonal trends

HWSS - Methodology

How do we sample?

Stratified random sampling

WHY?

• to obtain reliable estimates

for rural and remote areas

• try and eliminate selection

bias

• try and obtain a sample

that is representative of the

population

What mode of collection do we use?

Computer Assisted Telephone Interview (CATI)

WHY?

• cost

• timeliness

• higher response rates

HWSS - Methodology

What is our sample frame?

White Pages

WHY?

• provides us with address

information – this is used for

approach letters, geocoding

and stratifying by area

• easy to explain to

respondents

• relatively cost effective

Do we weight the data?

Yes

WHY?

• adjust for sampling method

• standardise to age and sex

distribution of WA population

• provide population estimates

HWSS – response rates

Excluded or under-represented in the sample frame

Culturally and Linguistically Diverse (CALD)

Aboriginal and Torres Strait Islanders

Mobile only households

Those without a listed telephone number

Updating the sample frame

New suburbs

Change in population demographics

Types of questions that can be asked over the phone

Challenges

Minimum level of English required to take part in

interview

Less than 0.2% of sample in pilot year needed an

interpreter (compared to 2% estimated by ABS)

70% of sample is Australian Born (compared to 63% in

2011 Census)

Culturally and linguistically

diverse (CALD) groups

Aboriginal and Torres

Strait Islanders

1.5-2% of sample in identified as Aboriginal or Torres

Strait Islander (compared to 3% estimated by ABS)

15% of Kimberley sample (compared to almost 40%

estimated by the ABS)

Different demographic profile

More likely to be female, older, and earn more than

$40,000 per annum

Mobile-only households

Only listed mobile phones are available in our sample

(~10% of sample)

Limited data on number of mobile-

only households (9-20%) and no data

on unlisted mobile-only households

Mobile-only population different to

landline population (younger, lower

income, renters, possibly different

health behaviours)

Unlisted telephone

numbers

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 1 2 3 or more

Per

cen

t

Number of listed telephone numbers

2003 2007 2012

0

10

20

30

40

50

60

70

16-24 years 25-64 years 65+ years

Pe

rce

nt

Listed phone number Unlisted phone number

Listed vs. Unlisted

telephone numbers

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Current smoker Sufficent physical activity Unhealthy weight

Per

cen

t Listed phone number Unlisted phone number

Listed vs. Unlisted

telephone numbers

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Fruit Vegetables

Me

an

da

ily s

erv

es

Listed phone number Unlisted phone number

Listed vs. Unlisted

telephone numbers

Updating the sample frame

50

55

60

65

70

75

80

85

90

Ja

n-0

5M

ar-

05

Ma

y-0

5Ju

l-0

5S

ep

-05

No

v-0

5Ja

n-0

6M

ar-

06

Ma

y-0

6Ju

l-0

6S

ep

-06

No

v-0

6Ja

n-0

7M

ar-

07

Ma

y-0

7Ju

l-0

7S

ep

-07

No

v-0

7Ja

n-0

8M

ar-

08

Ma

y-0

8Ju

l-0

8S

ep

-08

No

v-0

8Ja

n-0

9M

ar-

09

Ma

y-0

9Ju

l-0

9S

ep

-09

No

v-0

9Ja

n-1

0M

ar-

10

Ma

y-1

0Ju

l-1

0S

ep

-10

No

v-1

0Ja

n-1

1M

ar-

11

Ma

y-1

1Ju

l-1

1S

ep

-11

No

v-1

1Ja

n-1

2M

ar-

12

Ma

y-1

2Ju

l-1

2S

ep

-12

No

v-1

2Ja

n-1

3M

ar-

13

Ma

y-1

3Ju

l-1

3

Hit

ra

te (

Pe

rce

nta

ge

of

co

nn

ec

tio

ns

)

Changed to the 2008/09 WhitePages® Using the 2004/05 WhitePages®

Updating the sample

frame

Largest increase in

population density (as a %) • Capel

•Inner Perth

•Wanneroo

•East Pilbara

•Ashburton

Largest decrease in

population density (as a %) Mullewa

Carnamah

Dalwallinu

Murchison

Can handle a wide variety of questions – single

response, multiple response, numeric, open-ended.

Can’t use visual aides or cues (e.g. pictures of different

alcoholic drinks)

Allows for self-report only

Types of questions that

can be asked via CATI

Possible solutions?

Dual-frame surveys – combine two sampling frames

(e.g. listed and unlisted; landline and mobile)

Mixed mode methods – e.g. online and CATI, drop and

collect and CATI

Sophisticated statistical methods – e.g. raking

Conclusions

No method is perfect

Be aware of limitations

There is no solution that will work for everyone

Acknowledge the strengths of different collection modes

Select the best method that you can realistically enact

within your situation

Contact details

Dr Sarah Joyce

Sarah.joyce@health.wa.gov.au

9222 4233