• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.917-929
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• 2017

Korean income data obtained from Korea Labor Panel Survey shows excessive zeros, which may not be properly explained by the Tobit model. In this paper, we analyze the data using a zero-inflated Tobit model to incorporate excessive zeros. A zero-inflated Tobit model consists of two stages. In the first stage, individuals with 0 income are divided into two groups: genuine zero group and random zero group. Individuals in the genuine zero group did not participate labor market since they have no intention to do so. Individuals in the random zero group participated labor market but their incomes are very low and truncated at 0. In the second stage, the Tobit model is assumed to a subset of data combining random zeros and positive observations. Regression models are employed in both stages to obtain the effect of explanatory variables on the participation of labor market and the income amount. Markov chain Monte Carlo methods are applied for the Bayesian analysis of the data. The proposed zero-inflated Tobit model outperforms the Tobit model in model fit and prediction of zero frequency. The analysis results show strong evidence that the probability of participating in the labor market increases with age, decreases with education, and women tend to have stronger intentions on participating in the labor market than men. There also exists moderate evidence that the probability of participating in the labor market decreases with socio-economic status and reserved wage. However, the amount of monthly wage increases with age and education, and it is larger for married than unmarried and for men than women.

• Journal of the Korean Data and Information Science Society
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• v.28 no.4
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• pp.853-862
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• 2017

In this study, we analyse the determinants of the youth employment rate of public agencies and local public enterprises. On the other hand the youth employment rate contains information of the youth employment rate and the size of the youth employment. We use pooled tobit model and panel tobit model since dependent variable is a censored form observed only in a certain area. The results of the analysis are summarized as follows. First, the panel tobit model is more statistically significant as compared to the combined tobit model. Second, the youth employment rate is more statistically significantly higher in 2014 and 2015 than in 2011. Third, the youth employment rate in public enterprises is more statistically significantly higher than that in local public agencies. Finally, the higher the average wage is, the lower the youth employment ratio is.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.339-348
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• 2021

This paper aims to analyze the production efficiency in Korea's ten service sectors using DEA and its determinants utilizing a truncated-Tobit regression model and a censored-Tobit regression model in 2010-2019. This paper found: First, the Korean service sector's production efficiency in general has been significantly low and polarized. Especially, the inefficiency resulted from the scale inefficiency in the 'sewerage waste management industry.' Second, in the determinants analysis, the results show the positive effect of the investment and R&D expenses on technical efficiency, while FDI and lobbying expenses illustrate the negative impact. Moreover, it seems that the larger the industry, the higher the efficiency. Thus, the future Korean government's economic policy for the service sectors requires a mixed and integrated policy of the macroeconomic aspect such as active investment and R&D activities with microeconomic aspect including a convergence of FDI and human capital.

• Environmental and Resource Economics Review
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• v.12 no.4
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• pp.559-577
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• 2003

This paper analyzes household bottled water and water purifier expenditures, taking into account three important characteristics: expenditures may be censored at zero, may be interdependent across expenditure type, and may be endogenously and jointly determined. Censoring, interdependence, and endogeneity of the two expenditures are examined through simultaneous equation bivariate Tobit model. Expenditure function parameters are estimated using a 1997 household survey data collected in Seoul. The study detected interdependence between the two expenditures in the data. Moreover, the coefficient of one expenditure variable is statistically significant in the other expenditure equation. Thus, the overall results show that the simultaneous equation bivariate Tobit model employed here is appropriate for this analysis of the two expenditures. Finally estimated income and household size elasticities of the expenditures are presented.

• Journal of Korea Port Economic Association
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• v.24 no.4
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• pp.349-361
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• 2008

There has been abundant empirical research undertaken on the technical efficiency of Korean ports. Most studies have focused on the use of parametric and non-parametric techniques to analyse overall technical efficiency. This paper utilizes data for the period 2000-07 to offer a heterogeneous perspective on the overall efficiency of Korean ports. The framework assumes that ports use one input to produce one output; the output and input include port export(import) and regional export(import). This paper also employs panel analysis and heteroscedastic Tobit model to show the effect of the explanatory variables on the port efficiencies. The panel analysis shows that the regional export/total export has negative effect on the export efficiency while the regional import/total import has not any relations with the import efficiency. The heteroskedastic Tobit model shows that both regional export ratio and regional import ratio have negative effects on the efficiency while the gross regional domestic product has not any significant relations with the import efficiency.

• Environmental and Resource Economics Review
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• v.14 no.2
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• pp.447-474
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• 2005

Respondents, in the willingness to pay (WTP) survey, may have preference intensity about their stated WTP values. This study elicited a post-decisional intensity measure for each observed WTP answer for gathering information on the degree of preference intensity. In order to deal with the WTP data with preference intensity, this paper considers using the Type 3 Tobit model. This is usually estimated by the parametric two-stage estimation method assuming homoskedastic and bivariate normal error structure. However, if the assumptions are not satisfied, the estimates are inconsistent. The author has tested the hypotheses of homoskedasticity and normality, and could not accept them at the 1% level. The assumptions required to estimate the parametric Type 3 model are, therefore, too strong to be satisfied. As an alternative the parametric model, this study applies a semiparametric Type 3 Tobit model. The results show that the semiparametric model significantly outperforms the parametric model, and that more importantly, the mean WTP from the parametric model is significantly different from that from the semiparametric model.

• The Korean Journal of Applied Statistics
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• v.27 no.6
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• pp.991-1002
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• 2014

Both Bayesian and maximum likelihood methods are efficient for the estimation of regression coefficients of various Tobit regression models (see. e.g. Chib, 1992; Greene, 1990; Lee and Choi, 2013); however, some researchers recognized that the maximum likelihood method tends to underestimate the disturbance variance, which has implications for the estimation of marginal effects and the asymptotic standard error of estimates. The underestimation of the maximum likelihood estimate in a seemingly unrelated Tobit regression model is examined. A Bayesian method based on an objective noninformative prior is shown to provide proper estimates of the disturbance variance as well as other regression parameters

• Journal of Korea Port Economic Association
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• v.27 no.3
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• pp.135-146
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• 2011

A voluminous research on efficiency employs the DEA(Data Envelope Analysis) models. There are, however, only very few that have an interest in the factors influencing such efficiencies. We, furthermore, do not see any studies which analyze the long-term efficiency of the logistics providers using the panel cointegration techniques. The purpose of this paper, hence, is to evaluate the efficiency, analyse its determinants and show a long-term relationship between turnover and the other variables employing the SBM(Slack Based Measure) model, Tobit model, the panel procedure and the FMOLS(Fully Modified OLS). The panel data are composed of 9 individuals and 6 years. The panel cointegrating vectors show that the group coefficient of asset and employees is not only significant but has expected signs, while some of the individual coefficients are insignificant or/and exhibit wrong signs. The panel cointegrating vectors from fully modified OLS also indicate that the estimated coefficients of the panel analysis tend to be overvalued and the asset influences the turnover far greater than the employee does.

• Journal of Korea Technology Innovation Society
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• v.19 no.3
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• pp.604-633
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• 2016

In this study, we attempt to identify factors that influence the performances of Korean firms regarding global R&D cooperation, and to derive policy implications for performance improvement. The hypothetic influential factors include firms' general characteristics, purposes and types of cooperation, technology, partners and their countries, and government support. We categorize the performances of global R&D cooperation into technological, economic, and strategic performance, and analyze the effects of those factors on each of the performances as well as the overall performance. We use a standard tobit model for the overall performance, while using a multivariate tobit model for the other performances to reflect the possible correlations among them. The survey data was collected from 162 Korean firms that had previously conducted or were currently conducting global R&D cooperation.

• Proceedings of the Technology Innovation Conference
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• 2009.02a
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• pp.435-452
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• 2009

기업의 지속적 성장을 위해 기술혁신은 필수적이다. 그 동안 기술혁신 성과에 영향을 미치는 기업 속성을 파악하는 연구가 다양하게 진행되었는데, 기업의 전략적 관심사인 연구개발 효과성의 측면에서 분석한 연구는 많지 않다. 또한 데이터의 한계로 인해 기업의 기술경영 전략의 영향은 고려되지 못했다. 본 연구는 연구개발과 특허라는 투입-산출 관계의 연구개발 효과성에 대한 기업 속성 및 기술경영 전략의 영향을 계량적으로 분석했다. 통계청의 "기업활동실태 조사" 데이터를 이용해 국내 4,722개 연구개발 기업을 대상으로, '특허수/연구개발 투자'를 종속변수로 하는 토빗 회귀분석을 수행했다. 가설검정의 결과는 다음과 같다. 첫째, 기업 규모, 다각화 등 기업 속성 뿐 아니라 기업은 전략적 제휴, e비즈니스시스템 도입 등 기술경영 전략을 통해 연구개발 효과성을 높일 수 있다. 둘째, 외국인자본비중이 높을수록 연구개발 효과성은 낮다 셋째, 연구개발 외주비중은 연구개발 효과성과 역U자형의 관계로, 연구개발 외주 비중이 31%인 수준에서 연구개발 효과성이 극대화된다. 본 연구는 기업 속성 뿐 아니라 기술경영 전략이 기업의 연구개발 효과성이라는 기술혁신의 성과에 중요함을 밝힘으로써 기업의 연구개발 전략에 대한 시사점을 제시했다.