Utilizing Mobile Random Digit Dialing (RDD) Sampling Frames for Population Surveys in low- and middle-income countries in Asia and the Pacific Islands region

As we’ve previously discussed RDD phone survey sampling in emerging regions like Sub-Saharan Africa, Latin America, the Middle East, and North Africa, developing nations within the Asia-Pacific Islands region also feature a notable surge in mobile phone adoption in other developing parts of the world. The Asia-Pacific (APAC), in particular, has seen a significant increase in mobile phone ownership over the past two decades, accompanied by a decline in household landline ownership or no adoption of fixed landline infrastructure at all. Consequently, the use of mobile surveys, especially those employing random-digit dialing, has become a prominent method for efficient data collection in this region as well.

However, conducting RDD surveys in the APAC region presents its unique challenges. One primary concern is ensuring that the sample is representative. Household surveys encounter complexities, as access and equal selection probability are not universal. This issue is particularly evident by the digital divide and uneven connectivity of many low and middle-income countries (LMICs) in the area.

Another challenge is conducting surveys in a culturally appropriate and sensitive manner, respecting local customs. This may entail adapting survey questions to the languages spoken by native and minority ethnic groups to ensure respondents fully comprehend the questions being asked. Given that cultural norms and sensitivities can affect respondents’ willingness to participate in surveys, especially on sensitive topics, researchers must navigate these nuances carefully to avoid causing discomfort or offense.

Despite these obstacles, mobile surveys using RDD sampling hold promise as a valuable means of gaining insights across various domains in emerging nations. Their utility becomes evident in tasks such as collecting data for international program development and assessment efforts.

Considerations

When fielding telephone surveys in low and middle-income countries from Asia and the Pacific Islands, several key considerations need to be taken into account due to the unique cultural and social characteristics of the region:

• Political Sensitivities:
• Diverse Language and Cultural Contexts:
• Access to Mobile Phones and the Digital Divide
• Representation of Minority Groups
• Telephone coverage and frame size

Political Sensitivities: 

Conducting surveys on politically sensitive topics or in countries with strict government control over information can pose risks to both researchers and respondents.

Diverse Language and Cultural Contexts: 

The Asia Pacific region is incredibly diverse, with numerous languages, cultures, and customs. Crafting surveys that are culturally sensitive and available in multiple languages can be challenging.

Access to Mobile Phones and the Digital Divide 

While mobile phone adoption is generally high in the region, there are still remote and rural areas with limited access to mobile networks. Ensuring representation from these areas can be a concern. There is a digital divide as well in the region, with urban areas having better access to the internet and smartphones compared to rural areas. This can affect the representativeness of survey samples.

Representation of Minority Groups:

Ensuring that phone surveys are representative of all demographic groups, including ethnic and minority populations, can be challenging due to language barriers and cultural differences.

Telephone coverage and frame size

Key metrics for determining whether a telephone sample frame is sufficient for covering the population are the telephone frame size, subscriber counts (active frame), and the population size of the countries:

Telephone frame size – the sum of all possible phone number combinations that can be generated according to the nation’s numbering plan,  number length, and available dialing codes and prefixes.

Subscriber count – represents the populations that can be reached via a phone number device and/or SIM card.

Population size – the total count of residents that live in the country.

From these key metrics, we can derive crucial information such as how wide the Active Rate (count of subscriptions/telephone frame*100)

And the Telephone Penetration rate:

(count of subscriptions/population*100) – Calculate the number of phone subscriptions per 100 inhabitants.

Phone coverage is the count of all inhabitants that have access to at least one mobile device or SIM card.

e.g. In China’s case, the metrics are:

Population*: 1,410,600,000 (2021)

Mobile phone frame size**: 4,700,000,000  

Subscriber count*:  1,732,661,400 (2021)

Active Rate: 36.8% of the frame is active ~37 of 100 random numbers are expected to be working numbers.

Penetration rate (per 100 inhabitants): 122.8% – indicated that inhabitants have access to more than one mobile number device and or sim card – hence they have a larger probability of being over-selected in a random sample. Does not have any indication of non-coverage.

*Source: World Bank (WBG), 2021

**Source: ITU Numbering Plan for China

One limitation when we have a high penetration rate among subscribers when calculating these metrics is the over-coverage of respondents owning 2 or more cell phones. This may cause duplication and/or overlapping responses. If individuals provide different phone numbers for each survey, it becomes challenging to identify and eliminate duplicate entries. Additionally, multiple numbers may indicate a higher level of technology adoption or socioeconomic status, leading to a potential bias in the sample towards individuals with greater access and resources.

Telephone phone coverage and most common survey topics:

Top 3 Countries with the Highest Cell Phone Ownership in APAC:

1. Vietnam: This Southeast Asian country has experienced a substantial increase in mobile phone ownership since 2010, reaching, according to the WBG,2021. The affordability of feature phones and smartphones has contributed to high ownership rates of 98%.

2. Indonesia: As one of the most populous countries in the Asia-Pacific region, has seen significant growth in mobile phone ownership, particularly due to the affordability of smartphones and widespread mobile network coverage, its mobile ownership rate is calculated at 90.8%.

3. Philippines: Another LMIC in the Asia-Pacific region with relatively high cell phone ownership rates – 87%. 

Top 3 Countries with the Lowest Cell Phone Ownership in APAC:

1. Papua New Guinea: Papua New Guinea, historically has the lowest cell phone ownership rates, particularly in rural and remote areas. The rugged terrain and limited infrastructure have posed challenges to mobile network expansion. It has by far the lowest mobile phone ownership rate in the entire region, with an ownership rate sitting at ~48%

2. Myanmar: While the country has experienced rapid growth in mobile phone adoption in recent years, it has relatively lower cell phone ownership rates compared to some of its neighbors. However, it is important to note that mobile phone penetration has been on the rise due to increased access and affordability, currently the ownership rate is at 75%.

3. Cambodia: This Southeast Asian country is also classified as an LMIC, it has lower mobile phone ownership rates compared to more developed countries in the region. However, the country has also seen increased mobile phone adoption in recent years. Its cell phone ownership is calculated at 83.8%

Mobile phone ownership in the Asia-Pacific region

The report showcases mobile phone coverage on the individual level among all APAC nations in the region. Source: WBG, 2021

Common Survey Topics for APAC:

Over the years, our sampling methods have facilitated phone interviews and have been instrumental in shaping the design of numerous international surveys across various domains. These efforts have been undertaken by a multitude of international organizations such as the World Bank Group, World Health Organization, UNWomen, and other United Nations Agencies, and think tanks like PEW Research Center and Gallup in fields such as:

International Relations:

• Views on neighboring countries and international alliances
• Trade and economic partnerships
• Geopolitical tensions and conflicts
• Foreign policy preferences

Economic Issues:

• Income and wealth distribution
• Employment and job satisfaction
• Consumer behavior and spending patterns
• Economic growth and development

Technology and Digital Trends:

• Internet and mobile phone usage
• E-commerce and online shopping habits
• Social media and digital platforms
• Technology adoption and digital literacy

COVID-19 and Pandemic Response:

• Public health measures compliance
• Vaccine acceptance and hesitancy
• Economic impacts of the pandemic
• Remote work and education experiences

Health and Healthcare:

• Access to healthcare services
• Healthcare infrastructure and quality
• Public health concerns and awareness
• Health insurance coverage

Advantages and Disadvantages of sampling survey respondents Using RDD Methodology for phone survey research in APAC

Advantages of Random-Digit Dialing sampling for mobile phone surveys

Among the biggest advantages of mobile sampling in the APAC region, we list:

Wide Geographic Coverage: 

Mobile random digit dialing samples can reach both urban and rural areas, helping researchers gather data from diverse geographical locations within the Asia-Pacific region.

Cost-Effective:

Compared to other survey methods like face-to-face interviews, mobile surveys can be more cost-effective, especially when dealing with large and geographically dispersed populations.

Minimal Sampling Bias: 

Minimal Sampling Bias: When executed correctly, RDD can minimize some forms of bias, such as selection bias, by reaching households with unlisted numbers or those without internet access.

Disadvantages of Random-Digit Dialing  sampling for mobile phone surveys

Nonresponse Bias

Response rates for telephone surveys, including mobile surveys, have been declining worldwide. Low response rates can introduce nonresponse bias, as certain groups are more likely to participate than others, potentially distorting the sample’s representativeness.

Increasing Survey Fatigue:

The proliferation of telemarketing and survey calls can lead to survey fatigue, making it harder to convince respondents to participate.

Coverage Issues:

In some remote or less-developed areas of the Asia-Pacific region, mobile network coverage may be limited, leading to the underrepresentation of these areas in random-digit dialing samples.

Best Practices for RDD Mobile Sampling in the APAC Region:

Multi-Language Surveys: 

Multilingual countries like India or Singapore, offer surveys in multiple languages to ensure inclusivity and a wider reach.

Understand Local Mobile Trends: 

Stay updated on mobile phone adoption and usage trends in each specific country within the APAC region. This knowledge will help you design surveys that are relevant to the local context.

Local Partnerships: 

Collaborate with local research organizations, universities, or survey companies that have knowledge of the local landscape and can assist with sampling and data collection.

Adaptation:  

Be prepared to adapt your survey strategy based on the unique challenges and circumstances encountered in each APAC country. What works in one country may not work in another.

In conclusion, mobile RDD sampling offers a dynamic and efficient approach to conducting survey research in the Asia-Pacific region. Leveraging the widespread use of mobile devices, this method allows researchers to connect with a wider and more diverse audience. However, it is essential to remain vigilant about potential challenges related to sample representation, response rates, and technological limitations. By following established best practices and tailoring surveys to suit the regional context, the sampling methodology emerges as a valuable tool for data collection across the Asia-Pacific region.

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About Sample Solutions

Sample Solutions is a member of the World Association for Public Opinion Research (WAPOR), the organization has presented on numerous occasions related to this topic and provides Dual-frame and single-frame RDD sampling for 170+ countries, including all countries in Asia-Pacific for CATI, SMS, and interactive voice response survey (IVR) survey modes. If you have a research project that may require an RDD phone sampling approach for a specific country, we warmly welcome you to request our complimentary Sampling Methodology Whitepaper and country factsheet from our RDD Sample Coverage Page.

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