• Survey Research
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• v.9 no.3
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• pp.55-69
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• 2008

In most telephone surveys in Korea, telephone numbers are selected from the directories. Inevitably, such samples may lack representativeness due to poor coverage rate. To resolve the problem, Kang et al.(2008) implemented RDD(random digit dialing) method for nationwide sampling in Korea. The aim of this study is to compare an RDD sample with a traditional telephone quota sample that were collected independently by two survey institutes commissioned by the KBS-MBC consortium for the 2007 Presidential Election of Korea.

• Survey Research
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• v.12 no.2
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• pp.77-88
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• 2011

Korean telephone surveys have been based on telephone directory and thus criticized for considerable under-coverage. Now, Korean survey institutions progress to random digit dialing (RDD) very actively. But still most surveys are administered by quota sampling, prone to assign heavier weights to social classes with more hours staying indoor. As a practical remedy, time-balanced quota sampling scheme was proposed by Huh and Hwang (2006). This study compares two telephone surveys on TV audience environment in Korea: RDD with conventional quota sampling versus RDD with time-balanced quota sampling.

• Survey Research
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• v.9 no.1
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• pp.1-22
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• 2008

Telephone directories ille still being used as the sampling frame in almost all fixed-line telephone surveys in Korea, causing potentially serious coverage error. RDD (random digit dialing) sampling is an obvious alternative to solve the problem. The aim of this paper is twofold: 1) proposal of RDD methodology suitable to the telephone system of Korea and 2) the identification of socio-demographic and socio-psychological differences between listed-number and unlisted-number respondents. Major findings of RDD telephone survey conducted experimental]y are as follows. 1) Population coverage by telephone directories is 60% or less. 2) Unlisted-number households have statistically larger income compared to listed-number households. 3) Unlisted-number households have smaller family size compared to listed-number households. 4) Unlisted-number respondents are more sensitive about confidentiality, leaks, 5) Unlisted-number respondents are more liberal compared to unlisted-number respondents. These facts suggest that directory-based telephone surveys tend to be biased in socio-economic aspects.

• Survey Research
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• v.10 no.1
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• pp.33-56
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• 2009

Landline telephone surveys of the population of households or individuals in Korea often use telephone directories as sampling frames. Recently, the frequency of unlisted numbers in the directories has been increased and the number of households without landline phones has become larger with a spread of mobile phones. Landline telephone coverage has currently reached to a level that raises concerns about the currently due to a coverage bias on the statistics in question. In this paper, we first present the distribution of telephone ownership in Korea and make a comparison with some selected countries. Second, we describe the characteristics of telephone directories. Next, we directly or indirectly estimate the telephone coverage rates of the frames, and show that it may nationally be lower than 65.6% based on additional information. We conclude with remarks about future studies to reduce coverage bias, including the developments of efficient random digit dialing sampling methods.

• Asian Journal for Public Opinion Research
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• v.11 no.3
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• pp.257-273
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• 2023

Conducting face-to-face surveys is difficult and cost prohibitive, necessitating a new attempt to build a probability-based panel in South Korea. Since 99.9% of adult Koreans own a mobile phone, mobile phone numbers provide a viable sampling frame. Random digit dialing (RDD) surveys were conducted August-December 2021. Of the 288,056 valid phone numbers dialed, 13,655 respondents between the ages of 19 and 69 completed a phone survey. These respondents were later invited by text message to join a panel; 3,202 of these (23.4% or 1.2% based on the number initially contacted) joined the panel. When compared to official government statistics like resident registration data, the census, or the Social Survey, this new probability-based panel can be said to be representative of the Korean population on the basis of age, gender, location, marital status, and household size after weighting is applied. However, even after weighting, panel members are more educated than the general population, white-collar workers and self-employed people are overrepresented, and blue-collar workers are underrepresented. As of February 2023, this panel has grown to 10,471 participants with plans to continue to invite more panel members in the same way. Based on the comparisons in this paper, we can regard this panel as a cost-effective, probability-based panel that may be used for various kinds of public opinion research, by researchers both within and outside of Korea. As we continue to refine and grow this panel, we hope it will become more widely used by researchers as well as provide a model for those building similar panels in other countries.

• Communications for Statistical Applications and Methods
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• v.16 no.6
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• pp.1031-1036
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• 2009

Under recent dramatic declines in response rates, various procedures have been considered among survey practitioners to reduce nonresponse in order to avoid its potential impairment to the inference. In the random digit dialing telephone surveys, substantial efforts are often required to obtain the initial contact for the screener interview. To reduce a burden with higher data collection costs, refusal conversion can be administered only to a random portion of the sample, reducing nonresponse (bias) with an expense of sample variability increment due to the associated weight adjustment. In this paper, we provide ways to determine the optimal subsampling rate using a linear cost model. Our approach for refusal subsampling is to predetermine a random portion from the full sample and to apply refusal conversion efforts if needed only to the subsample.

• Korean Journal of Health Education and Promotion
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• v.25 no.4
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• pp.13-28
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• 2008

Objectives: The purpose of this study was to assess general population' AIDS knowledge and attitudes towards AIDS. Methods: Using a multistage area sampling and random digit dialing method, a random sample of individuals aged 19-59 years, living in 16 different area in Korea during September 2007 were interviewed by telephone. Results: In all, 1,087 respondents completed the survey. In most items, respondents displayed a fairly good degree of knowledge about AIDS. However it was lower than that in developed countries. Respondents' attitudes towards AIDS were found to be negative. The knowledge and attitudes towards AIDS were more positive for respondents who were young, educated, office worker or students, higher in income. The higher level of knowledge, the more positive attitudes towards AIDS. Conclusions: In general AIDS related knowledge was relatively low and people showed negative attitudes towards AIDS. Incorrect knowledge and lack of information on AIDS would lead to unnecessary negative attitudes and there need to be addressed by health education programs and campaigns using mass media.

• Survey Research
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• v.12 no.1
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• pp.153-174
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• 2011

This research aims to discuss the causes of inaccuracy in public opinion polls currently conducted in Korea. In particular, identifying the problems in sampling frame and sampling methods in political and social public opinion polls is an important question. Currently, most polling organizations operating in Korea are using phone number directories provided by Korea Telecom(KT) as its sampling frame for conducting most political polls. A critical problem of using a phone number directory as a sampling frame is that unlisted phone numbers can never be included in the sample. If a systematic difference in socio-demographic or politico-economic characteristics exists between the listed number using group and the unlisted group, using a phone number directory as a sampling frame cannot produce a sample that can represent the whole adult population in Korea. According to the poll result commissioned by the Asan Institute for Policy Studies in January 2011, there are statistically significant differences in socio-demographic and politico-economic characteristics between those two groups, and those differences led to the differences in the presidential job approval rating and party support. Our findings include that the listed number using group is more pro-Grand National Party and show stronger support for the president than the unlisted group.

• Journal of Contemporary Eastern Asia
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• v.14 no.1
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• pp.5-22
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• 2015

This study examines how different uses of social network sites (SNS) and mobile phones (MP) to communicate with friends and business associates are related to the acquisition of job-related information, job mobility, and entrepreneurial intentions, using social capital as its main theoretical lens. To this end, a nationally representative, random digit dialing (RDD) survey was conducted in Singapore. Path analyses show that SNS interactions with friends are positively related to both bonding and bridging social capital. The former is linked with greater job mobility, the latter with entrepreneurship, and both are associated with more job-related information. SNS interactions with business contacts are directly positively related to job-related information and entrepreneurship. For mobile phones, interactions with friends are positively related to social capital, job information and entrepreneurship. Professional networking is associated with more bridging social capital, job information and job mobility. Bonding capital is found to be linked with greater job mobility, while bridging capital has a positive relationship with both entrepreneurship and job mobility.

• Journal of Chest Surgery
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• v.49 no.sup1
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• pp.44-52
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• 2016

Background: This study investigates the perception of the general public regarding the concentration to metropolitan, hospitals of cardiac and cerebrovascular surgeries, and the perceived public need for government policies to resolve this issue. Methods: A total of 800 participants were recruited for our telephone interview survey. Quota sampling was performed, adjusting for age and sex, to select by various geographic regions. Sampling with random digit dialing was performed; we called the randomly generated telephone numbers and made three attempts for non-responders before moving on to a different telephone number. Results: Our sample population was 818 participants, 401 men (49.0%) and 417 women (51.0%). Our data showed that 85.5% of participants thought that cardiac surgery and neurosurgery patients are concentrated in large hospitals in Seoul. The principle reason for regional patients to want to receive surgery at major hospitals in Seoul was because of poor medical standards associated with regional hospitals (87.7%). We found that a vast majority of participants (97.5%) felt that government policies are needed to even out the clustering of cardiac surgery and neurosurgery patients, and that this clustering may be alleviated if policies that can specifically enhance the quality and the capacity of regional hospitals to carry out surgeries are adopted (98.3%). Conclusion: Government policy making must reflect public desiderata, and we suggest that these public health needs may be partially resolved through government-designated cardiac and neurosurgery specialist hospitals in regional areas.