• The Korean Journal of Applied Statistics
• /
• v.19 no.1
• /
• pp.57-67
• /
• 2006

In sampling survey, nonresponse tend to occur inevitably. If we use information from respondents only, the estimates will be baised. To overcome this, various non-response imputation methods have been studied. If there are few auxiliary variables for replacing missing imputation or spatial autocorrelation exists between respondents and nonrespondents, spatial autocorrelation can be used for missing imputation. In this paper, we apply several nonresponse imputation methods including spatial imputation for the analysis of farm household economy data of the Gangwon-Do in 2002 as an example. We show that spatial imputation is more efficient than other methods through the numerical simulations.

• The Korean Journal of Applied Statistics
• /
• v.27 no.7
• /
• pp.1229-1241
• /
• 2014

Most of sampling surveys have outliers and non-response missing values simultaneously. In that case, due to the effect of outliers, the result of imputation is not good enough to meet a given precision. To overcome this situation, outlier treatment should be conducted before imputation. In this paper in order for reducing the effect of outlier, we study outlier imputation methods and outlier weight adjustment methods. For the outlier detection, the method suggested by She and Owen (2011) is used. A small simulation study is conducted and for real data analysis, Monthly Labor Statistic and Briquette Consumption Survey Data are used.

• Journal of Korea Technology Innovation Society
• /
• v.5 no.2
• /
• pp.228-244
• /
• 2002

The survey of research and development (R&D) in science and technology (S&T) covers the current status of R&D activities in S&T in Korea, and provides a basis for decision making regarding S&T policy. Continuous improvement of the survey is widely needed to present reliable national basic statistics. Therefore, the purpose of the study is two-fold: to introduce sampling survey method in industrial sector and to make statistical technique to deal with non-response data from industrial sector. To these ends, first, case studies of the United States and Japan are illustrated. A new sampling design for the R&D survey is proposed and implementing stratified random sampling scheme is suggested. Moreover, statistical analysis of the non-response data is dealt with. Based on several screening criteria, we develop a new imputation method suitable for the R&D survey and also provide more detailed implementation plan. Various solutions to a problem arising from non-response item are also presented. Finally, some implications of the results are discussed.

• 정보화사회
• /
• s.151
• /
• pp.58-61
• /
• 2001

한국정보통신산업협회에서는 지난 1995년부터 정부 정보통신부문 공식 통계 승인기관으로 정보통신부문 산업통계조사를 지속해 왔다. 본 실태조사는 2001년 3월 1일까지 교육인적자원부에 등록된 4년제 대학 186개교 중 2001년 4월 6일부터 5월 16일까지 정보통신기술인력의 기초 현황조사에 응한 정보통신부문 대학을 포함하는 143개 대학교를 대상으로 한 ‘정보통신기술인력 실태 조사’ 결과이다. 단, 무응답(non response)대학은 Sequetial Hot-Deck Imputation방법을 통해서 보정하였다.

• The Korean Journal of Applied Statistics
• /
• v.27 no.6
• /
• pp.1003-1016
• /
• 2014

Proper missing data imputation is an important procedure to obtain superior results for data analysis based on survey data. This paper deals with both a model based imputation method and model estimation method. We utilized a Bayesian method to solve a boundary solution problem in which we applied a maximum likelihood estimation method. We also deal with a missing mechanism model selection problem using forecasting results and a comparison between model accuracies. We utilized MWPE(modified within precinct error) (Bautista et al., 2007) to measure prediction correctness. We applied proposed ML and Bayesian methods to the Korean presidential election exit poll data of 2012. Based on the analysis, the results under the missing at random mechanism showed superior prediction results than under the missing not at random mechanism.

• The Korean Journal of Applied Statistics
• /
• v.27 no.3
• /
• pp.501-512
• /
• 2014

Modified cut-off sampling is widely used for highly skewed data. A serious drawback of modified cut-off sampling is the difficulty of adjustment of non-response in take-all stratum. Therefore, solutions of the problems of non-response in take-all stratum have been studied in various ways such as substitute of samples, imputation or re-weight method. In this paper, a new cut-off point based on minimizing MSE being used in exponential and power functions is suggested and it can be reduced the number of take-all stratum. We also investigate another cut-off point determination method with underlying distributions such as truncated log-normal and truncated gamma distributions. Finally we suggest the optimal cut-off point which has a minimum of take-all stratum size among suggested methods. Simulation studies are performed and Labor Survey data and simulated data are used for the case study.

• Journal of the Korean Data Analysis Society
• /
• v.20 no.6
• /
• pp.2873-2881
• /
• 2018

It is very important to obtain objective and credible information through election polls in order to contribute to the correct voting behavior of the voters or to establish appropriate election strategies for candidates or political parties. Therefore, many related organizations such as political parties, media organizations, and research institutions have been making efforts to improve the accuracy of the results of the polls and the election prediction. Kim et al. (2017) analyzed whether the non-response group responded that there is no support candidate in the election survey to increase the accuracy of the estimation of the vote rate. As a result, it has been confirmed that the accuracy of the estimation of the vote rate can be significantly improved by performing an appropriate classification on the non-response layer. In this study, we propose a method to estimate the turnout by each strata (sex, age group) under the condition that the total turnout rate is given for a specific district (region) and propose a procedure to predict the vote rate by reflecting the turnout. In addition, case studies were conducted using data gathered through telephone interviews for the 20th National Assembly elections in 2016.

• Survey Research
• /
• v.9 no.3
• /
• pp.71-91
• /
• 2008

Workplace Panel Survey(WPS) is the representative panel survey of workplace in Korea. WPS was newly sampled in 2005 and is to be used for the subsequent biennial survey. The main survey is divided into a questionnaire for human resources(HR) manager, a questionnaire for labor relations manager and a questionnaire for representatives of unions. The population of WPS 2005 included workplaces across the country with 30 or more employees. The WPS 2005 was composed of 1,905 workplaces including 290 workplaces in the public sector. The sample was selected by the stratified random sampling. Weighting process for the survey data was introduced to compensate for differential sampling and non-response rates. Personal interviews were conducted using the Computer Assisted Personal Interviewing(CAPI) system during visits by interviewers, along with survey via mail and e-mail concerning employment and financial issues. The CPAI system introduced for the WPS 2005 can by used for automatical detection for errors and inconsistencies which may occur during the survey process. The CAPI system played an important part in enhancing the reliability of the survey data.