Apr 20, 2023 1

Measuring Disability in Censuses and Household Surveys

Mitchell LoebNational Center for Health Statistics, USAfor the Washington Group on Disability Statistics

Apr 20, 2023 2

This presentation will cover:

• Disability definition and the International Classification of Functioning, Disability and Health – ICF

• Disability measurement and the Washington Group on Disability Statistics – WG

• An example of disability prevalence measurement from a recent Zambian survey

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Our understanding of disability has changed:

from: a medical definition – based on a medical

condition as an individual pathology

to:a concept based on the consequences of

diseases; on functional capacity and social participation

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Moving from Concept to Definition to Measurement:

The Conceptual Model

ICF selected as the conceptual model:• Common point of reference • Common vocabulary

• Does not provide an operational definition or a way to measure the concepts

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Health Condition(disorder/disease)

Body Function &Structure (Impairment)

Activities(Limitation)

Participation(Restriction)

EnvironmentalFactors

PersonalFactors

Source: World Health Organization, 2001

The ICF Model

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Moving from Concept to Definition to Measurement:

The Definitional Paradox• There is no single operational definition

of disability• Different operational definitions lead to

different estimates• The question you are trying to answer

(the purpose) will determine which definition to use

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Purpose of Data Collection3 major classes of purposes at aggregate

level• Service Provision• Monitoring functioning in the population• Assess equalization of opportunities

2 criteria for selection of a purpose• Relevance—particularly for policy makers

and program officials• Feasibility

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Purpose: Equalization of opportunities

• Seeks to identify all those at greater risk than the general population of experiencing restrictions in social participation, for example in employment, education or civic life

• Disability as a demographic

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Moving from Concept to Definition to Measurement:

Measurement of equalization of opportunities

• Locate the definition of disability at the most basic level of activity/participation in core domains• Defined as the ability or inability to carry out

basic actions at the level of the whole person (i.e. walking, climbing stairs, lifting packages, seeing a friend across the room)

• Connection between ‘disability’ and participation can be made during data analysis

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Health Condition(disorder/disease)

Body Function &Structure (Impairment)

Participation(Restriction)

EnvironmentalFactors

PersonalFactors

Source: World Health Organization, 2001

Locating Risk in the ICF Model

?

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Possible question optionsMobility• Walking• Climbing stairs• Bending or stooping• Reaching or lifting• Using handsSensory• Seeing• HearingCommunicating• Understanding• Speaking

Cognitive functions• Learning• Remembering• Making decisions• ConcentratingEmotional functioning• Interpersonal interactions• Psychological well-being

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Criteria for inclusion of domains

• Cross cultural comparability• Suitability for self-report• Parsimonious• Validity across various methodological

modes

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WG short set of questions for censuses:Because of a Health problem:1) Do you have difficulty seeing even if wearing glasses?2) Do you have difficulty hearing even if using a hearing

aid?3) Do you have difficulty walking or climbing stairs?4) Do you have difficulty remembering or concentrating?5) Do you have difficulty with (self-care such as) washing

all over or dressing?6) Using your usual (customary) language, do you have

difficulty communicating (for example understanding or being understood by others)?

Response categories: No - no difficulty; Yes - some difficulty; Yes - a lot of difficulty; Cannot do at all

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What do we end up with?

• Identify persons with similar types and degree of limitations in basic actions regardless of nationality or culture

• Represent the majority (but not all) persons with limitations in basic actions in any one nation

• Represent commonly occurring limitations in domains that can be captured in the Census context

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Intended use of data• Compare levels of participation in

employment, education, or family/social life for those with disability versus those without disability to see if persons with disability have achieved social inclusion

• Monitor effectiveness of programs / policies to promote full participation can be monitored

• Monitor prevalence trends for persons with limitations in specific basic activity domains

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Limitations• One set of measures will not satisfy the

multiple needs for disability data• Excluded populations:

• Very young children• Institutionalized population• Homeless• Floating populations

• It is not our purpose to:• identify every person with a disability within

every community • replicate a population evaluated across a wider

range of domains that would be possible with other forms of data collection

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An Example:

Disability prevalence in Zambian:Data collected in a national household survey, 2006

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The Disablement Process ca.1980

Disease or Impairment(s) Disability(ies) Handicap(s)

disorder Body level Personal level Societal level

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Measuring Disability: 1Measurement based on impairments: the ”What’s

wrong with you?” approach.

Questions used to identify persons with disabilities:Zambia Census 1990

1. Are you disabled in any way? Yes/No2. What is your disability?

Blind Yes/NoDeaf/dumb Yes/NoCrippled Yes/NoMentally retarded Yes/No

Disability prevalence = 0.9%

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Disability prevalence

0

20

40

60

80

100

non-disabled disabled

Disability status

Per

cen

t o

f p

op

ula

tio

n

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Global disability prevalence rates*High-income countries Low-income countries

Year % Year %

Canada 1991 14.7 Kenya 1989 0.7

Germany 1992 8.4 Namibia 1991 3.1

Italy 1994 5.0 Nigeria 1991 0.5

Netherlands 1986 11.6 Senegal 1988 1.1

Norway 1995 17.8 South Africa 1980 0.5

Sweden 1988 12.1 Zambia 1990 0.9

Spain 1986 15.0 Kenya 1989 0.7

UK 1991 12.2 Zimbabwe 1997 1.9

USA 1994 15.0 Malawi 1983 2.9

* Sources and methodologies are country specific

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Measuring Disability: 2

Zambia Census 2000

“…disability refers to a person who is limited in the kind or amount of activities that he or she can do because of on-going difficulties due to long term physical, mental or health problems.”

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Measuring Disability: 2

Questions used to identify persons with disabilities:Zambia Census 2000

1. Are you disabled in any way? Yes/No2. What is your disability?

Blind Yes/NoPartially sighted Yes/NoDeaf/dumb Yes/NoHard of hearing Yes/NoMentally ill Yes/NoEx-Mental Yes/NoMentally retarded Yes/NoPhysically handicapped Yes/No

Disability prevalence = 2.7%

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Health Condition(disorder/disease)

Body Function &Structure (Impairment)

Activities(Limitation)

Participation(Restriction)

EnvironmentalFactors

PersonalFactors

Source: World Health Organization, 2001

The ICF Model - 2001

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Measuring Disability: 3Because of a Health problem:1) Do you have difficulty seeing even if wearing glasses?2) Do you have difficulty hearing even if using a hearing aid?3) Do you have difficulty walking or climbing stairs?4) Do you have difficulty remembering or concentrating?5) Do you have difficulty with (self-care such as) washing all

over or dressing?6) Using your usual (customary) language, do you have

difficulty communicating (for example understanding or being understood by others)?

Response categories: No - no difficulty; Yes - some difficulty; Yes - a lot of difficulty; Cannot do at all

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Measuring Disability: 3

The survey of Living Conditions among People with Disabilities in Zambia (2006) used the short set of 6 WG questions.

Response categories: No difficulty, Some difficulty, A lot of difficulty, Unable to do it

At least two of six Domains have at least some difficulty• prevalence 13.4%

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Sample prevalence (%) by domain and degree of difficulty

Core DomainSome

difficultyA lot of

difficultyUnableTo do it

Vision 4.7 2.6 0.5

Hearing 3.7 2.3 0.5

Mobility 5.1 3.8 0.8

Remembering 2.0 1.5 0.3

Self-Care 2.0 1.3 0.4

Communicating 2.1 1.4 0.5

At least:

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Overall Sample prevalence (%)

Person with disability has: N %

at least 1 Domain is ‘some difficulty’ 4053 14.5

at least 2 Domains are ‘some difficulty’ 3090 11.0

at least 1 Domain is ‘a lot of difficulty’ 2368 8.5

at least 1 Domain is ‘unable to do it’ 673 2.4

more than 1 Domain is ‘some difficulty’ 1718 6.1

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Work on Extended Measures• The WG is developing an extended set of

questions that:• goes into greater depth on the same 6

domains covered by the short set of questions, and

• includes additional domains of functioning such as learning, affect, pain and fatigue,

• includes questions about age at onset and impact of the difficulty,

• is currently being cognitively tested in preparation for subsequent field testing.

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RowVision (1) Hearing (1) Mobility

Communi-cation

Cognition/ remembering

Upper Body

Learning/ understanding

Affect Pain FatigueADL/ IADL

Getting Along with

People

Life Activities

Participation in Society

Short SetSingle Questions (1) d a d

Extended SetMultiple Questions (1) c c c c

Use of Assistive DevicesMicro-E (2)

Functioning with Assistance, Micro-E (2)

5 Age at Onset

6 Cause

7 Duration

8 Impact ? ? ?

9Meso-Environment

(3)

10Macro-Environment

(4)

ICF Chapter Reference - Activities/Participation

ICF-1 ICF-1 ICF-4 ICF-3 ICF-1,2 ICF-4 ICF-1 ICF-2 ICF-5,6 ICF-7 ICF-8 ICF-9

Capacity Perform

ance

Basic Activity Domains Complex Activity Domains

(5) See Note below

Washington Group/Budapest Initiative/UNESCAP Activities and Workplan

QuestionnaireTopic/Type

To be obtained through other sources, not personal survey data collections

b

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  Basic activity domains

Question topic Mobility

Short set  Do you have difficulty walking or climbing steps?

 Do you have difficulty moving around inside your home?

Functioning without assistance

1. Do you have difficulty walking 100 (meters/yards) on level ground, that would be about the length of one (1) football field or one (1) city block?

2. Do you have difficulty walking half a km/ a third of a mile on level ground, that would be the length of five (5) football fields or five (5) city blocks?

3. Do you have difficulty walking up or down 12 steps?

ProbeHow much difficulty would you have going up or down those steps without using a handrail?

Use of AD/Micro-Environment

1. Do you use any equipment or receive help for getting around? 2. Do you use any of the following?Cane or walking stick? Walker? Zimmer frame? Crutches? Wheelchair? Prothesis(es)? Someone’s assistance? Other?

Functioning with Assistance

1. Do you have difficulty walking 100 (meters/yards) on level ground, that would be about the length of one (1) football field or one (1) city block, when using your aid?

2. Do you have difficulty walking half a km/ a third of a mile on level ground, that would be the length of 5 football fields or 5 city blocks, when using your aid?

3. Do you have difficulty walking up or down 12 steps, even when using your aid?

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Mobility SeverityDifficulty walking 100 meters

on level ground

None A little A lot Total

Difficulty walking half a km on level ground

None 4993 3 0 4996

A little 426 360 7 793

A lot 34 201 159 394

Cannot do it

3 13 26 42

Total 5456 577 192 6225

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  Basic activity domains

Question topic Anxiety

Short set  

 How often do you feel worried, nervous or anxious? Daily, Weekly, Monthly, A few times a year, Never

Use of AD/Micro-Environment

Do you take medication for these feelings?

Functioning: Extended questions

1. Thinking about the last time you felt worried, nervous or anxious, how would you describe the level of these feelings?

A little, A lot, Somewhere in between a little and a lot2. Would you say this was closer to a little, closer to a lot, or exactly in the

middle?

Probe:

Please tell me which of the following statements, if any, describe your feelings.

1. My feelings are caused by the type and amount of work I do.2. Sometimes the feelings can be so intense that my chest hurts and I

have trouble breathing.3. These are positive feelings that help me to accomplish goals and be

productive.4. The feelings sometimes interfere with my life, and I wish that I did not

have them.5. If I had more money or a better job, I would not have these feelings.6. Everybody has these feelings; they are a part of life and are normal.7. I have been told by a medical professional that I have anxiety.

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Anxiety Severity

How often do you feel worried, nervous or anxious?

A few timesa year Monthly Weekly Daily Total

Thinking about the last time you felt worried, nervous or anxious, how would you describe the level of these feelings?

A little 1087 423 328 214 2052

In between

179 126 161 104 570

A lot 163 86 122 259 630

Total 577 1429 635 611 577

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  Basic activity domains

Question topic Pain

Short set  

Functioning: Extended questions

 Do you have frequent pain?

In the past 3 months, how often did you have pain? Never, Some days, Most days, Every day?

Thinking about the last time you had pain, how long did the pain last? Some of the day, Most of the day, All of the day?

Thinking about the last time you had pain, how much pain did you have? A little, A lot, Somewhere in between a little and a lot?

Would you say the amount of pain was closer to a little, closer to a lot, or exactly in the middle?

Probe:

Please tell me which of the following statements, if any, describe your pain.1. It is constantly present.2. Sometimes I’m in a lot of pain and sometimes it’s not so bad.3. Sometimes it is unbearable and excruciating.4. When I get my mind on other things, I am not aware of the pain.5. Medication can take my pain away completely.6. My pain is because of work.7. My pain is because of exercise.

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Pain Severity

In the past 3 months, how often did you have pain?

NeverSomedays

Mostdays

Everyday Total

Thinking about the last time you had pain, how long did the pain last?

Some of the day

28 1545 146 126 1845

Most of the day

5 237 181 115 538

All of the day

6 272 154 187 619

Total 39 2054 481 428 3002

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Additional domain specific Extended questions

Age at onset How old were you when the difficulty walking or climbing began?

Impact

How much does your difficulty walking or climbing limit your ability to carry out daily activities?

• Working to support you or your family?• Working outside the home to earn an income?• Going to school or achieving your education goals?• Participating in leisure or social activities?• Getting out with friends or family?• Doing household chores such as cooking and cleaning?• Using transportation to get to places you want to go?• Participating in religious activities?• Participating in community gatherings?

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Meeting Products & Information

• Executive summary of last eight WG meetings posted on the Washington Group website along with presentations & papers from the meetings:• http://www.cdc.gov/nchs/citygroup.htm

• Publication of key papers in a special issue of Research in Social Science and Disability