Workshop on Improving Disability Data for Policy Use
23-26 September 2003, Bangkok, Thailand

Questionnaire on Survey and Census of National Disability Data

National Statistical Office, Thailand

1. Overview of survey or census

               The National Statistical Office (NSO) collected disability data for the first time in 1970 Population and Housing Census. The data had been collected in the Health and Welfare Survey since 1974, and repeated in 1976, 1977, 1978, 1981, 1986, 1991, 1996 and 2001.

Table 1 Number and percentage of disabled persons by source of data.

(Number in Thousands)

Source : National Statistical Office, Ministry of Information and Communication Technology

The statistical system of Thailand is decentralized system. Besides the NSO, another agencies also collected disability statistics as well. Concepts, definitions and classification are different among agencies, pertaining to the purpose of data are to be used.

There are many problems in conducting disability survey, e.g,

• lack of standard concept, definition and classification
• lack of special sampling frame,
• interviewers have no experience on medical knowledge,
• interviewers need skill training on technical language used for interviewing people with disabilities,
• questions on disabilities are not standard for various purposes and for comparison across agencies,
• etc.

               The NSO had tried to improve these problems by reviewing concepts, definitions and classifications, developing methodology and coordinating with some major users of the survey. The first independent Disability Survey was carried out in 2002.

1. Title of survey or census
   Disability Survey.
2. Date of latest data collection
   2002.
3. Periodicity of survey or census
   Every 5 years.
4. Contact person(s) for the survey/census

1. Ms. Pakamas Rattanalangkarn
   Socio-Economic Statistician,
   Statistical Forecasting Bureau,
   National Statistical Office,
   Larn Luang Road, Bangkok 10100
   Phone : 02 2810333 ext. 1407
   Fax : 02 2825861
   Email : pakamas@nso.go.th

2. Ms. Navarat Opanapun
   Socio-Economic Statistician,
   Bureau of Social-Economic Statistics
   National Statistical Office,
   Larn Luang Road, Bangkok 10100
   Phone : 02 2810333 ext. 1217
   Fax : 02 2818617
   Email : navarat@nso.go.th

2. Brief summary of survey or census

a.   Describe what information on disability is collected

1. Demographic and characteristics of persons with disability : age, sex, marital status, education and working.
2. Persons aged 13 years and over having health problems or chronic illness consecutively for 6 months and over or having impairments, type of health problems, problems in performing activities (such as mobility, standing, walking upstairs, seeing, hearing, dexterity, recognition, emotion and communicating with other people), aged and caused of health problems and the using of aid equipment.
3. Persons aged 13 years and over having health problems and having problems in performing the activities of daily living (ADLs) and carer.
4. Persons having impairments, type of impairment, person who judge or diagnose the type of impairments, aged and caused of impairments, place where the impairment occurred, requirement and type of government needed, knowing about the Rehabilitation of Disabled Persons Act B.E. 2534 (1991), receiving health insurance and source of receiving.

b. What uses are made of the data and who are the users?

The data obtained from the survey will benefit for developed policies, programs and services for the disabled and also use to provide education, occupation, health, social, etc. In the field of health and population use to estimate Disability-Free Life Expectancy.

The users of the survey are

• Ministry of Public Health
• Ministry of Social Development and Health Service
• Sirindthorn National Medical Rehabilitation Centre
• Ratchasuda Foundation
• Disabled Peoples International Asia Pacific Region
• etc.

c.   Were users involved in deciding what information to collect?

Yes, they were.

d.   What definition of disability was used?

The definition of Disabled Person of the 2002 Disability Survey was developed by basing on the Rehabilitation of Disabled Persons Act B.E. 2534(1991).

“Disabled person” refers to person with either at least one of characteristics as follows :

1. Impairment in terms of sight refers to person who could not absolutely see or could not see properly which is not corrected by wearing glasses or contact lenses, i e, blindness, low vision eye etc. They have to use an aid equipments i. e. magnifying glass (for low vision person) or the Braille alphabet (for the blind) etc.
2. Impairment in terms of hearing or communication refers to person who has impairment or difficulties in hearing, which resulted to use of an aid equipments i. e hearing aid or sign/body language or other non-spoken form of communication.
   Impairment of communication refers to person who has difficulties understanding or being understood by others or has malfunctioning certain part of brain, which causes inability to understand others.
3. Impairment in terms of physical or locomotion refers to person who has difficulties to walk or move, such as
   • Obvious incomplete use of arms, legs, feet, fingers
   • Loss of mobility of arms, legs, feet, fingers due to malfunctioning of limb or weakness
4. Impairment in terms of mentality or behavior refers to person who has impairment of nervous or emotional condition that restricted everyday activities.
5. Impairment in terms of intellectual or learning ability refers to person who has limitation in learning or understanding compared to general people.

In the 2002 Disability Survey, the concept of disability is the consequent of health problems or chronic illness consecutively for 6 months and over or impairment which limit that person from performing the principle activities as normal people.

e. Were data collected and compiled according to international standards or national classifications and definitions? (e. g. ICIDH or ICF)

Yes, they were. We applied the classification of diseases and illness of World Health Organization, ICIDH or ICF, which related to impairment and disability.

3. Scope of survey or census

a.   Described the population covered in the survey (age, private dwelling population, institutionalised population, etc.)

The 2002 Disability Survey covered private and special households which members have health problems or chronic illness consecutively for 6 months and over or have impairments.

4. Coverage and sampling

a. Coverage of survey or census

According to the concept of the 2002 Disability Survey, the coverage of the survey covered private and special households which members have health problems or chromic illness consecutively for 6 months and over or have impairments. The scope was well achieved.

b. Sample frame (s) (sample size)?

The special sampling frame was carried out by adding some questions related the concept of the survey to the Basic Household Information Survey (listing survey) Listing of sample households was made prior to the survey. The sample households were selected systematically from a completing list of households in each sample blocks and villages.

The total sample size was 49,997 households, of which 2,745 households were in Bangkok Metropolis, 24,360 households in other municipal areas and 22,892 households in non-municipal areas.

5. Are there other data sources which you use to benchmark your survey results?

No, there are not. Even though, the National Statistical Office had collected disability data in the Health and Welfare Survey during 1974-2001, but the concept, definition, methodology, etc. were different from the 2002 Disability Survey. Therefore, the result of the survey could not be compared.

6. Response and non-response

a.  What was the response rate?

= 40,992 / 49,997 X 100 = 82 %

b.  Did you evaluate the non-response?

The NSO classified the non-response into sources, i. g. vacant house, demolished house, went to the sample households 3 times but could not see the respondents, incooperate, etc. We didn’t follow-up the non-response households and impute the missing data.

7. Data collection (Attach or mail us a copy of your questionnaire)

We have the questionnaire only in Thai language, so we didn’t attach or mail.

a. Manner of collection

Face-to-Face interviewing method.

b. Type of respondent

Before interviewers went to the sample households. They made the appointment with those households. Sometimes, they could see all members of the sample households (including disabled person) and sometimes they could not.

The interviewers were assigned to interview every member of sample households. If they could not do that they had to interview proxy, the head or members of sample households who could respond to the questions.

c. Format of questions

The questionnaire of the 2002 Disability Survey consists of 4 parts :

Part 1 : Demographic characteristics of household members

Part 2 : Education

Part 3 : Working

Part 4 : Impairment and Disability

There were about 70 questions, some questions were close-ended and some were open-ended. We developed pre-coded by recommendations of specialists, studying and past experiences.

d. List the languages used in the survey or census

Thai language

8. Measurement error

a. Which special data collection procedures were undertaken to reduce measurement error?

In the stage of planning, the questionnaire and manual instruction were drafts and pretests. One month prior to field work, the enumerators were trained. During the field work, supervisors and subject matters went out to observe and supervise enumerators, helping them tackled some problems which occurred.

9. Highlights of the strengths and limitations of survey or census

Strengths :

• Large scale statistical survey at National Level.
• Using statistical methodology.
• Having quality control at every stage.
• Using international standard concept
• Having specialist to be advisors.
• Major users, especially disabled persons, participated in planning : specified concept, definition and classification including draft the questionnaire.
• etc.

Limitations :

• Concept, definition and classification are not standard.
• Lack of special sampling frame.
• Questions are not standard for various purposes and for comparison across agencies.
• Interviewers have no experience on medical knowledge and need skill training on technical language which used for interviewing people with disabilities.
• Respondents in the sample households have various background of education and always view disability as the inferior characteristic ofhouseholds which try to conceal
• etc.

10. List published sources on disability statistics

• Health and Welfare Survey 1974, 1976, 1977, 1978, 1981, 1986,
  1991, 1996, 2001, National Statistical Office,
  Ministry of Information and Communication Technology
• Disability Survey 2002, National Statistical Office,
  Ministry of Information and Communication Technology

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