Methodology and Quality Update

Latest Update on Methodology and Quality

04/05/2026

Statistical Presentation

Data description

Disability Statistics present detailed data on persons with disabilities in Saudi Arabia. They aim to provide data and indicators to measure changes over time. The data are presented through tables, charts, and analytical reports.
It is a statistical product conducted to collect data on the main characteristics as follows:
•    Functional domains of disability.
•    Demographic characteristics (age, sex, nationality).
•    Single and multiple disabilities.
Data is also used to estimates:
•    Prevalence of disability among the population. 
•    Distribution of disability by functional domains.
•    Distribution of disability by single and multiple disabilities.

Classifications

The following classifications are applied in the disability survey.
International Classification of Functioning, Disability and Health (ICF):
It is a conceptual framework issued by the World Health Organization and serves as the international reference for measuring disability from a functional perspective based on the interaction between health conditions and environmental and personal factors. It focuses on an individual’s ability to function and participate in society rather than solely on medical diagnosis.
This framework is used as a methodological basis for developing disability measurement tools, including the Washington Group on Disability Statistics questions, which are based on the concept of functional difficulties across different life domains. This enhances international comparability and contributes to producing indicators that support evidence-based policies.
International Classification of Functioning, Disability and Health (ICF) – World Health Organization
Washington Group Extended Set of Disability Questions (WG-ES):
The Washington Group Extended Set of Disability Questions (WG-ES) is an internationally recognized statistical tool issued by the Washington Group on Disability Statistics. It is conceptually based on the International Classification of Functioning, Disability and Health (ICF), issued by the World Health Organization. It consists of an extended set of questions designed to measure functional difficulties in greater detail by capturing the level of difficulty individuals experience across multiple functional domains.
The (WG-ES) questions cover several functional domains, most notably:
•    Difficulty seeing.
•    Difficulty hearing.
•    Difficulty in movement (walking or climbing stairs):
•    Difficulty communicating.
•    Difficulty in both remembering and concentrating
•    Difficulty in self-care.
•    Difficulty in upper body movement (arms).
•    Difficulty using hands and fingers.
WG Extended Set on Functioning (WG-ES) Washington Group on Disability Statistics
National Code of Countries and Nationalities (3166 ISO – codes Country):
A statistical classification based on the international standard  (ISO 3166_Country codes), which is a standard issued by the International Organization for Standardization (ISO of the UN), and this classification gives numeric and literal codes for the world’s (248) countries, based on the classification of countries. 
The classification is used in the disability survey to classify Saudi or non-Saudi individuals.
Detailed data are collected through interviews to enable the production of outputs in accordance with all relevant classifications.
The classifications are available on GASTAT’s website:   www.stats.gov.sa

Statistical concepts and definitions

Concepts and Definitions – Disability Statistics:
•    Disability (according to the World Health Organization):
Disability results from the interaction between individuals with health conditions and environmental and personal factors that may limit their full and effective participation in society on an equal basis with others.
•    Functional difficulties (according to the Washington Group on Disability Statistics):
These are the difficulties an individual faces in performing basic activities of daily living, measured using standardized questions based on a unified scale of difficulty levels.
•    Definition of disability (according to the Washington Group methodology):
Persons with disabilities are defined as individuals who reported having a lot of difficulty or being unable to perform a function.
•    Person with disability (according to the Disability Rights Law):
Any person with a long-term impairment in physical, mental, intellectual, sensory, or psychological functions that, when interacting with various barriers, may prevent their full and effective participation in society on an equal basis with others.
•    Difficulty seeing:
ِA challenge in vision, even when using prescription glasses, including difficulty seeing or recognizing objects at near or far distances.
•    Difficulty hearing:
A challenge in hearing, even when using hearing aids, includes difficulty hearing sounds or understanding speech.
•    Difficulty in mobility:
A challenge in walking, climbing stairs, or using limbs affects an individual’s ability to move and perform daily activities.
•    Difficulty in remembering or concentrating:
A challenge in remembering information or concentrating while performing daily activities affects the ability to learn or complete tasks.
•    Difficulty in self-care:
A challenge in the ability to care for oneself, such as bathing or dressing.
•    Difficulty in communication:
A challenge in understanding others or expressing thoughts using speech or other means of communication.

Data sources

The main source of Disability Statistics data is the Population Characteristics Survey 2025.
The main variables published for Disability Statistics data 2025 are:
•    Disability prevalence.
•    Prevalence of functional difficulty.
•    Functional domains of difficulty. 

Designing the data collection tool

Data is collected using a questionnaire prepared and designed by specialists at the General Authority for Statistics (GASTAT). The data collection tool is developed in an electronic format (CAPI) to ensure ease of use by field researchers. In its design, international recommendations, standards, and definitions are taken into account. The questionnaire is also shared with relevant entities to obtain their views and feedback. Furthermore, the questions are formulated clearly and scientifically to standardize the wording and guidance of questions. 
Sections of the questionnaire:
•    Geographic data. 
•    Basic data. 
•    Demographic characteristics of household members.
•    Difficulties. 
•    Volunteering.
•    Lifestyle and quality of life.
•    Housing data.
Method of calculating the indicators:

Review and validation rules:
Validation and consistency rules are incorporated into the questionnaire to ensure that the collected data is consistent, accurate, and logical. These rules are developed by establishing logical relationships between responses, questions, and various variables to assist field researchers in detecting any errors directly during data entry.
To ensure the quality of the Population Characteristics Survey data, three types of validation and editing rules were established, as follows:
•    Navigation rules between sections and fields:
Special rules were programmed to regulate automatic navigation between sections and fields, based on the respondent’s input, totaling 63 rules.
•    Error rules:
Rules that cannot be bypassed during the data entry process. The field researcher must correct the data by referring back to the respondent to verify its accuracy. The total number of these rules exceeds 107.
•    Warning rules:
Rules established to verify the accuracy of the field researcher’s data entry. The field researcher may override these rules if the data is confirmed to be correct. The total number of these rules is 10.

Questionnaire test (cognitive test)

Cognitive testing was conducted on several questionnaire items. Interviews were conducted on a random sample of the population and dwellings distributed across the regions of Saudi Arabia. 
During the cognitive testing process, the following evaluation pillars were taken into consideration: The overall concept of the question, clarity of question wording, clarity of the terms used in the question, appropriateness of response options, participants’ ability to answer the questions effectively, and the extent to which participants are willing to provide responses were assessed, leading to the preparation of a report summarizing the overall results of the cognitive test.

Statistical population

The statistical population of Disability Statistics consists of the population and dwellings of persons with disabilities in Saudi Arabia.

Sample Design

The sample was designed using a stratified cluster random sampling method. The total sample size amounted to 192,729 private housing units and 7,239 public dwellings. The distribution of the sample across the administrative regions is as follows:  
Table1: Sample distribution at the administrative region level:

Sample type:
The sample was designed using a two-stage stratified cluster systematic random sampling method, in which a random sample of primary sampling units is selected in the first stage from each stratum of the approved sample design. In the second stage, a systematic random sample of 25 housing units is selected within each selected primary sampling unit. 
Stratification:
To increase the efficiency of the sample and enhance its representation of the target population, the primary sampling units in the sample frame were classified into homogeneous strata as follows: In order to obtain more accurate results compared to a simple random sample of the same size, and to ensure a sufficient number of households at publishable levels with acceptable precision, stratification was conducted as follows:
•    Governorates were used as actual strata to meet the need to produce survey indicators separately for each governorate.
•    The level of urbanization was used to define the actual strata as follows:
-    Attended.
-    Rural.
Size of sample:
The sample size was calculated at the level of Saudi Arabia and then allocated to the administrative regions using exponential allocation (based on the level of urbanization). Subsequently, the sample of each administrative region was distributed across its governorates using probability proportional to size. The resulting sample size at the stratum level (governorate × level of urbanization) was adjusted so that it is not less than 120 housing units .λ=0.4  The sample size amounted to approximately 192,729 private housing units and 7,239 public dwellings. 
Sample size estimation formula:

The sample size of the target units for the survey in each stratum (h) (domain of study) is calculated as follows: 

Whereas: 
•    :  It is the sample size for each stratum (study domain). 
•    : It is the estimated design effect for each stratum (study domain).
•    : It is the estimated response rate for each stratum  (study domain). 
•    : Allowed relative error in estimating the indicator for each stratum (study domain). Note that the allowable error is calculated by multiplying the relative error    by the value of the proportion to be estimated from the survey  
•   : It is the most important proportion to be estimated from the survey for each stratum  (study domain). 
•    : It is the confidence level coefficient for the proportion in stratum  (study domain). 
Sample allocation to strata:
In this survey, the total sample size was calculated at the level of Saudi Arabia and then allocated to the thirteen administrative regions using power allocation with a power parameter (λ = 0.4). Subsequently, the sample of each administrative region was allocated to its strata (governorates and levels of urbanization) using proportional allocation. This allocation enhances the precision of estimates by improving the design effect through reducing the variability of weights.

Statistical unit

The statistical unit in Disability Statistics is the individual with a disability.

Data collection

Data are collected for Disability Statistics Through Computer-Assisted Personal Interviewing (CAPI). 
The data is stored in GASTAT's databases after undergoing auditing and review processes following approved statistical methods and recognized quality standards. If errors or discrepancies are detected, the data is cross-referenced with the data source for correction or clarification.

Data collection frequency 

Data collection for Disability Statistics through the Population Characteristics Survey is conducted periodically between the Population and Housing Censuses.

Reference area

Disability Statistics cover all 13 administrative regions of Saudi Arabia.

Reference period (time reference)

Reference period of the variables or dataset is as follows:
•    Data on the number of family members and their demographic characteristics are based on the date of contact with the family and interviews with its members.
•    Age is calculated with reference to the survey launch date (27 April 2025).

Base period

Not applicable, as Disability Statistics provide data and indicators related to persons with disabilities periodically to measure changes over time and are not compared to a fixed base period.

Measurement unit

All results are calculated as percentages (such as Disability prevalence rate).

Time coverage

Data are available from 2017 to 2025.

Publication frequency

The results of Disability Statistics from the Population Characteristics Survey are published periodically between the Population and Housing Censuses.

Statistical processing

Error detection

Meticulous processes were implemented to detect errors in the data collected, using automated and manual methods aimed at ensuring quality and accuracy.
These included the following:
•    Identification of illogical or out-of-range values (such as impossible ages or contradictory data).
•    Detecting missing or incomplete data and handling them according to established policies.
•    Reviewing internal consistency among questionnaire responses.

Data integration and matching from multiple sources 

Not applicable, as the data are based on a single primary source only.

Imputation and calibration

How to calculate sampling weights:
Sample weights were calculated by computing the design weight, which reflects the probability of selecting a sampling unit in the sample, so that the weight of a selected unit (individual) in the sample is as follows

Where:
  It is the symbol for the probability of selecting an individual i from the stratum h 
Adjustment of weights for non-response:
The weights were adjusted to compensate for non-response or missing data to ensure sample representativeness. This adjustment is made after data collection and identifying response status, and is calculated using the following formula:

Where:
   The non-response adjusted weight for the stratum (or adjustment class),    where the adjustment factor for each stratum (or adjustment class) f_hNR is calculated as follows:

Where:
 The symbol R denotes the response cases (respondents), and   denotes the non-response cases (non-respondents) in the final weight adjustment (weight calibration). 
While the survey indicators relate to the individual rather than the household, the weights are calibrated (adjusted) to align with the population distribution based on known characteristics such as age, sex, nationality, and administrative region, as follows:
•   Post-strata adjustment classes are constructed based on a combination of the above-mentioned variables, and the latest population totals for each adjustment class are obtained from population estimates. 
•   The sums of non-response adjusted weights are calculated within each adjustment class. 
•   The weight calibration factor is calculated by dividing the population totals by the sums of weights within each adjustment class. 
The following equation illustrates the weight calibration mechanism.

Where:
•    :  Represents the final weight of individual  in post-stratum after weight calibration
•    :   Represents the non-response adjusted weight of individual in post-stratum
•     :  Represents the total number of individuals in post-stratum based on population estimates.
•     : Represents the sum of non-response adjusted weights in post-stratum  

Seasonal adjustments

Not applicable, only final results will be published.

Adjustment of preliminary results 

Not applicable, only final results will be published. 

Resources used

Quality dimensions

Suitability

A criterion that measures the extent to which the product meets users’ needs.

User needs 

Internal users at (GASTAT) Disability Statistics data:
•    Social statistics
•    Department of customer support.
Several external users significantly benefit from the data of Disability Statistics, including:
•    Government entities.
•    Regional and international organizations.
•    Research institutions.
•    Media.
•    Individuals.
Key variables that external users benefit from:

Completeness 

Disability Statistics data are based on field survey data from the Population Characteristics Survey, to provide comprehensive information on persons with disabilities in Saudi Arabia, including disability prevalence, as well as the types and levels of disability.
The completeness of the data was ensured through specialized electronic systems that prevent switching between questions without filling in the mandatory fields, in addition to field monitoring and subsequent quality assurance reviews.

Accuracy and reliability 

A measure of the extent to which estimates or calculations are close to the actual values that reflect reality.

Overall accuracy 

•    Data quality is enhanced through the selection of researchers based on a set of practical and objective criteria related to the nature of the work, as well as their qualification and training.
•    Alert, prevention, and correction rules are applied during the data collection process on the electronic questionnaire of the Population Characteristics Survey to improve data quality.
•    The data is examined against previous years to identify any significant changes.
•    The internal consistency of the data is checked before it is finalized.
•    The links between variables are checked and coherence between different data series is confirmed.

Timeliness and punctuality

Timeliness A standard that indicates the length of time between the availability of information and the occurrence of the event.
Punctuality It reflects the time lag between the data publication date and the target date when publication actually occurs.

Timeliness 

GASTAT is committed to applying internationally recognized standards regarding the announcement, clarification of the time of publishing statistics on its official website, as outlined in the statistical calendar, as well as adhering to the announced time of publication. In the event of any delay, updates will be provided accordingly.

Punctuality 

Publication is carried out in accordance with the release dates set in the Statistical Calendar for the Demographic Characteristics Survey published on GASTAT’s website.
The data are available at the expected time, as scheduled in the statistical release calendar, If the publication is delayed, reasons shall be provided.

Coherence and comparability

A standard that refers to the necessity of internal and temporal consistency of statistics, their logical coherence, and their comparability and integration across different regions and sources.

Comparability - geographical

Data are fully comparable geographically at the administrative region, regional, and international levels.

Comparability - over time 

Disability statistics were introduced within the Demographic Characteristics Survey in 2017 and are based on the Washington Group Short Set methodology, which measures six functional difficulties. In line with updates from the Washington Group, the questions on disability statistics were further developed within the Demographic Characteristics Survey 2025.
 The main changes are as follows:
•    The Washington Group Short Set (WG-SS) was used in the Demographic Characteristics Survey 2017 and the Census 2022.
•    The number of functional difficulties was six.
•    The Demographic Characteristics Survey 2017 targeted individuals aged 2 years and above.
•    The Census 2022 covered all age groups.
•    The Washington Group Extended Set (WG-ES) was used in the Demographic Characteristics Survey 2025.
•    The number of functional difficulties increased to eight based on the tool used.
•    The target age group for social surveys was updated to 5 years and above in line with the Washington Group.

Coherence- Cross domain

Disability statistics data is subject to standardized validation and processing procedures. Its consistency is verified through comparison with data published in other publications, such as the 2022 Census, ensuring the coherence of indicators and preventing inconsistencies across different statistical publications.

Coherence- Sub-annual and annual statistics 

Not applicable, as disability statistics are produced through the Demographic Characteristics Survey conducted between two censuses (every 10 years).

Coherence- National Accounts 

Not applicable, as disability statistics are produced through the Demographic Characteristics Survey and are not linked to the national accounts, as they target the population.

Coherence- Internal 

Disability statistics are internally consistent, as all indicators and data for the reference period are based on the same validated dataset.

Accessibility and clarity

It refers to users’ access to data, the availability of detailed and aggregate data, and the availability of the Methodology and Quality Report.

Press releases

The announcements for each publication are available on the statistical calendar as mentioned in 10.1. The press releases can be viewed on the website of GASTAT on the link: 
Press release

Publications

GASTAT issues the Disability Survey publications and reports regularly within a pre-prepared dissemination plan and is published on GASTAT’s website. GASTAT is keen to disseminate its results in a manner that serves all users, including publications in various formats containing dissemination tables, charts of data and indicators, the Methodology and Quality Report, and the survey questionnaires used, in both Arabic and English.
The results of Disability Statistics are available at the following link:
Disability Statistics

Online database

Not available.

Microdata accessibility

Accurate data is unit-level disaggregated data obtained from multiple sources such as sample statistical surveys, general population and housing censuses, and administrative systems, providing detailed information about the characteristics of individuals, families, business entities, and geographical areas, supporting the construction and development of statistical indicators and scientific research.
Different types of microdata files are available to meet diverse information needs.
•    Public use: 
It consists of sets of records containing information on individuals, households, or business entities anonymized in such a way that the respondent cannot be identified either directly, such as by name, address, contact number, identity number, etc., or indirectly (by combining different – especially rare – characteristics of respondents), such as age, occupation, education, etc.
•    Scientific use:
These datasets are created in accordance with specific methodologies upon request of data users to extract datasets with defined characteristics for use in strategic studies, decision-making, and scientific research for individuals, households, and enterprises, while ensuring that they do not contain any direct identifiers and are subject to confidentiality protection controls.
Qualified users who meet the standards and procedures of confidentiality protection can access the files of scientific use of accurate data through the platform "ITAHA" of the General Authority for Statistics, while the most sensitive data for use is shared by visiting the accurate data laboratory within a secure environment managed by the Authority.

References and standards

•    Washington Group on Disability Statistics:
Washington Group

Quality assurance

GASTAT ensures that the following principles are taken into account: Impartiality; ensuring that the statistical product is user-oriented; quality of processes and outputs; effectiveness of statistical operations; and reduction of the burden on respondents. 
Data is validated through procedures and quality controls that are applied during the process at various stages, such as data entry, data collection, and other final controls.

Quality assessment

GASTAT carries out all statistical activities in accordance with the National Version of the Generic Statistical Business Process Model (GSBPM). During the comprehensive evaluation stage, which is the final stage of the GSBPM, information collected across all stages and sub-processes is used to prepare an evaluation report that summarizes all challenges related to the quality of each statistical process and serves as input for improvement and development actions.

Confidentiality

Confidentiality - Policy

According to Royal Decree No. 23 dated 07/12/1379, data must always be kept confidential and must be used by GASTAT for statistical purposes only.
Therefore, the data is protected in the data servers of GASTAT.

Confidentiality - Data Treatment

Data of SMEs survey are presented in right tables in order to summarize, understand, as well as extract their results. Moreover, to compare them with other data, and to obtain statistical significance about the selected study population. However, referring to such data indicated in tables is much easier than going back to check the original questionnaire that may include some data like names and addresses of individuals, and names of data providers, which violates data confidentiality of statistical data.
“Anonymity of data” is one of the most important procedures. To keep data confidential, GASTAT removed information on individual persons, households, or business entities in such a way that the respondent cannot be identified either directly, such as by name, address, contact number, identity number, etc., or indirectly by combining different, especially rare, characteristics of respondents, such as age, occupation, education, etc.

Dissemination policy

Statistical calendar

Disability Statistics have been included in the Statistical Calendar. 
Statistical Calendar

User access

GASTAT prioritizes meeting users' needs for statistical data. Accordingly, the results of Disability Statistics 2025 will be made available through official channels immediately upon release, ensuring easy and timely access to the data.
Customer questions and inquiries regarding the publication and its results are also received through various communication channels, such as:
•    GASTAT official website:  www.stats.gov.sa
•    GASTAT official email address:  info@stats.gov.sa
•    Official visits to GASTAT’s official head office in Riyadh or one of its branches in Saudi Arabia.
•    Official letters.
•    Statistical telephone: (199009).