The Definition and Measurement of Disability: The Work of the Washington Group

(continued)

Daniel MontDisability and Development Group

The World Bank

November 9, 2006

Cognitive Testing Cognitive testing was undertaken in 15 countries to

ensure validity and better understand how the questions operate.

Purposive Samples Asked WG question and series of detailed questions in

the same domains Collected information on response process Analyzed problematic response patterns Questions performed well with a few issues:

• Glasses and hearing aid clauses

• Communication question

More detailed questions on functioning. For example, Cognitive Questions

Do you have difficulty remembering the names of people or places? Do you have difficulty remembering appointments? Do you have difficulty remembering how to get to familiar places?

Do you have difficulty remembering important tasks, like taking medications or paying bills?

Do you have difficulty concentrating on doing something for ten minutes?

Do you have difficulty learning a new task, for example, learning how to get to a new place?

Do you have difficulty finding solutions to problems in day to day life?

Information on response process

Questions to interviewers• Need to repeat any part of the question?

• Any difficulty in using response options?

• Did respondents ask for clarification or qualify their answers?

Follow-up probes to understand response process

Correlates of cognition difficulty

Unadjusted ORs

95% Conf. Int.

Concerned 11.18*** 7.34 – 17.05

Learn new task 7.93*** 4.95 – 12.70

Problem solving

7.22*** 4.59 – 11.35

Correlates of cognition difficulty

Difficulties remembering

Unadjusted ORs

95% Conf. Ints.

People or places

9.12*** 5.85 – 14.23

Appointments 6.55*** 4.36 – 9.82

Finding places 5.20*** 3.43 – 7.86

Important tasks 6.40*** 4.27 – 9.60

Socio- demographic correlates of cognition difficulty

Unadjusted ORs

95% Conf. Ints.

Male

1.04 (non-sig) 0.70 – 1.54

Age

35-54

55 +

1.05 (non-sig)

2.05***

0.64 – 1.72

1.26 – 3.33

Overall, questions worked well

Well understood Responses consistent Two problem areas

• Glasses clause – WG is revisiting but solution has a lot to do with translation protocol

• Communication Question – WG will revisit to see if question can be simplified

Field Testing

Undertaken in South Africa and Vietnam Checking for Internal consistency Results comparable to changes seen in

other countries with move towards functional approach to measuring disability

WG Census Question vs. Extended Questions For Field Test

Constructed three thresholds for disability based on WG census question: D1=1 if any difficulty, D2=1 if a lot, D3=1 if unable to do

Constructed three thresholds for disability based on extended questions: ED1, ED2, ED3

What was the D measure picking up compared to the ED measures?

Example: Mobility question WG question:

• Do you have difficulty walking or climbing steps? • D1=1 if “some difficulty”, “a lot of difficulty”, or “cannot do at all”

• D2=1 if “a lot of difficulty” or “cannot do at all”

• D3=1 if “cannot do at all” Extended Questions:

• Do you have difficulty going outside of your home?(0)

• Do you have difficulty walking a long distance such as a kilometer (or a mile)?• ED1=1 if “some”, “a lot” or “cannot do” for either question

• ED2=1 if “a lot” or “cannot do at all” for either question

• ED3=1 if “cannot do at all” for either question

South Africa : N=185D vs ED (2, 3 or 4 Qs)

01020304050607080

No.

of r

espo

nden

ts

D1 (High) D3 (Low) ED1 (high) ED3 (Low)

Vietnam Disability Rates – Thai Binh Province

Seeing N Pct.

No Difficulty 2390 70.3

Some Difficulty 803 23.6

A Lot of Difficulty 184 5.4

Unable 23 0.7

Walking or Climbing Steps

N Pct.

No Difficulty 2637 77.6

Some Difficulty 564 16.6

A Lot of Difficulty

176 5.2

Unable 23 0.7

Functional Questions Lead to Higher Rates of Disability Many Developing Country Censuses ask “Do

you have a disability?” but…• People think of disability as very serious and won’t

report minor or moderate disabilities• “Disability” creates shame and stigma so people do

not want to identify themselves that way, • People think of disability relative to their expectations

of normal functioning so it undercounts the elderly Switch to Functional Questions raises disability

rate• E.g., Brazil 14.5%, Ecuador 12.1%, Zambia 13.1%,

Nicaragua 10.3%

But, no such thing as a single prevalence rate

In Ecuador, 12.1% of the population has a disability but 4% are significantly disabled. Which is the right number?

In a field-test of WG questions in India, 4% of the population has great difficulty walking or cannot walk, but 18% of the population has some difficulty walking? Which is the right number?

It depends why you are asking

SINTEF study in Zambia (Loeb and Eide)

Nationally representative sample WG questions as screen All disabled respondents asked detailed

follow-up activity limitation questions Sample of non-disabled respondents

asked similar questions

9 Domains & 44 Activities

1. Basic learning & applying knowledge: reading, writing2. Communication: producing and receiving messages3. Mobility: walking, moving around4. Self-care: washing, dressing5. Domestic life: shopping, preparing meals6. Sensory experiences: watching, listening7. Interpersonal relations: making friends, interacting with

strangers8. Major life areas: going to school, getting a job9. Community, social and civic life: clubs, religious, politics

Activity Limitation (a measure of capacity)

How DIFFICULT it is for you to perform this activity WITHOUT ASSISTANCE?

0 - no difficulty 1 - slight difficulty 2 - moderate difficulty 3 - severe difficulty 4 - unable to carry out the activity

Activity Limitations

0

20

40

60

80

100

120

140

160

180

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 82 86 90 94 98 102 108 112 119 126 143 161

Nu

mb

er

dis

ab

led

0

2

4

6

8

10

12

14

16

18

20

Nu

mb

er

No

n-d

isa

ble

d

Disabled

Non-disabled

Activity limitation score

Disability Data Collection Recommendations

Do not use the word disability Functional approach Separate functional domains Scaled Responses Definition of disability can be made ex

post, and hinge on domains and thresholds used