• Survey Research
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• v.5 no.1
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• pp.27-49
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• 2004

Recently, in several countries including South Korea, the percentage of households having fixed telephones, which is often called the fixed telephone coverage rates, has decreased due to a rapid spread of mobile phones. It is generally assumed that the lower the rates of coverage, resulting in a major frame undercoverage problem, the greater the possibility of the bias. In this paper, we first take a look at the changes of coverage rates in both fixed telephones and mobile phones in South Korea and examine the coverage rates by sociodemographic characteristics of households. Also, we refer to a change in the level of fixed telephone noncoverage and the resulting problems in the situation. Second, we provide a comparison of the coverage rates for households for some European countries, the United States, Canada etc. Finally, we suggest further research to rise to our research environments increasingly troublesome, owing to the wide spread of mobile phones.

• Survey Research
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• v.13 no.1
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• pp.135-158
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• 2012

Korean telephone surveys have been based on landline telephone directory or RDD(Random Digit Dialing) method. These days, however, there has been an increase of the households with no landline, or households with the line but not willing to register in the directory. Moreover, it is hard to contact young people or office workers who are usually staying out of home in the daytime. Due to these issues above, the predictability of election polls gets weaker. Especially, low accessibility to those who stay out of home when the poll's done, results in predictions with positive inclination toward conservatism. A solution to resolve this problem is to contact respondents by using both mobile and landline phones-via landline phone to those who are at home and via mobile phone to those who are out of home in the daytime(Mixed Mode Survey, hereafter MMS). To conduct MMS, 1) we need to obtain the sampling frames for the landline and mobile surveys, and 2) we need to decide the proportion of sample size of both. In this paper, we propose a heuristic method for conducting MMS. The method uses RDD for the landline phone survey, and the access panel list for the mobile phone survey. The proportion of sample sizes between landline and mobile phones are determined based on the 'Lifestyle and Time Use Study' conducted by Statistics Korea. As a case study, 4 election polls were conducted in the periods of the special election for the mayor of Seoul on Oct 26th, 2011. From the initial 3 polls, reactions and responses regarding the issues raised during the survey period were appropriately covered, and the final poll showed a very close prediction to the real election result.