• 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 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.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.15-24
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• 2011

This study discusses an equity analysis performed to supplement the existing bus service evaluation system. The equity of 179 feeder bus routes in the city of Seoul(Year 2009) is analyzed by employing the modified BCC model along with the desirable inputs such as a number of bus stops and a frequency of operations. In the analysis, each DMU (Decision Making Unit) is assumed to use the desirable inputs, and produces both the index of equity and the index of accessibility. We apply an input-oriented modified BCC model to analyze the equity of the DMUs. The computational result indicates that only 9% of the feeder bus routes are equitable among the total DMUs and the average equity estimate is 0.702. It is also suggested that on average approximately 60% increases of desirable inputs (i.e., a number of bus stops and a frequency of operations) are needed in order to improve equity of DMU in the city of Seoul. The result of the tobit regression analysis on the determinant factors affecting the equity of DMUs shows that all the independent variables (i.e., a number of bus stops and a frequency of operations) are statistically significant at 5% significance level, and the number of bus stops is found to be the most influential factor.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.45-53
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• 2009

This study presumes the efficiency of each route by utilizing data of Seoul's exclusive bus routes for the 2008 and the DEA model. In the estimation, it is assumed that the number of passengers and profits of each route is calculated by considering the number of buses and stops, travel distance, intervals and management cost. This study computed the efficiency scores of each bus line in Seoul based on the data for the first half of 2008 and one of the DEA models, namely the BCC model. After analysis using the input-oriented BCC model, out of a total of 18 lines of interest, there were 2 CRS lines and 16 IRS lines. Also, the Tobit Regression Analysis that helps identify the impact of the elements used in the analysis on efficiency scores proved that the most influential element to exclusive buses is the length of intervals.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.43-54
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• 2010

In order to improve the existing evaluation system of bus services and gain more reasonable analysis outputs, the authors evaluate the efficiency of 113 arterial bus routes in Seoul in 2009 using a modified BCC model considering not only desirable outputs but also undesirable outputs. Each Decision Making Unit (DMU) is assumed to use inputs such as possession costs, operating costs, the ratios of median bus stops overlapped route lengths to produce estimates of desirable outputs (the number of passengers and service satisfaction score) and undesirable outputs (CO2 emissions). According to the analysis, the modified BCC model considering both desirable outputs and undesirable outputs shows more appropriate results. DMUs would be more efficient on average to reduce nearly 10% of the 3 inputs (possession costs, operating costs, and overlapped route lengths) and increase by about 160% the ratios of median bus stops. Also, a Tobit regression analysis is conducted to identify the most effective variables for maximum efficiency and discover that the variable of possession costs and the ratios of median bus stops are statistically significant.

• Journal of Korea Water Resources Association
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• v.57 no.6
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• pp.393-407
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• 2024

This study was conducted with the purpose of focusing on local water supply services, identifying equity and influencing factors, and analyzing the results. Using the Coulter model for 152 local governments across the country, equity was measured for six variables, including average unit price, rates of recovering costs from water price, revenue water ratio, water supply rate, number of employees, and customer satisfaction. Among them, the level of inequality in the average unit price was the highest. As a result of trend analysis, the degree of equity of most variables decreased. In addition, through Tobit analysis, factors influencing equity such as financial independence, local tax burden, and administrative district level were confirmed. In order to provide equitable water supply services, institutional changes such as rate increases are needed. And the government and local governments must pursue various water supply plans.

• Journal of Korean Society of Transportation
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• v.20 no.2
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• pp.59-68
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• 2002

Using 1996 annual observations for 69 bus firms in Seoul, this paper measures firm-level efficiency with data envelopment analysis(DEA) and identifies firm characteristics indicative of differential efficiency in these firms with Tobit regression analysis. The paper then conceptualizes that these firms produce two kinds of output(city/seat bus kilometers or city/seat bus Passengers) using four inputs (labor vehicle, fuel and maintenance). The findings show that, on an average, these firms have only a little input saving potential of 0.9 percent, while not a little output increasing potential of 12.9 percent. On the other hand, it is discovered that these firms operate more efficiently with a lower ratio of maintenance employees to total employees. Furthermore, it appears that both the ratio of seat buses to total buses and average speeds positively affect efficiency in this industry.

• 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 Korea Society of Industrial Information Systems
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• v.28 no.1
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• pp.71-82
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• 2023

As an alternative to solving social problems, social economic actors are attracting attention as an important alternative. SPC is a private program that pays incentives according to the social performance measured by monetary value. This study measured efficiency by applying DEA to social enterprises that participated in the SPC program and analyzed the factors affecting efficiency through tobit regression. As a result of DEA analysis, it was found that 21% of social enterprises participating in SPC were efficient, but 66% needed to improve their efficiency. In the Tobit regression analysis, the efficiency was relatively low in the case of manufacturing sector, and when the square term of sales is included, the efficiency decreases as sales increase. Through this, it was estimated that external support is needed at a low level sales before crossing the critical point, and that the efficiency of social value creation increases when it grows above a certain level. Moreover, it is significant in that it combines the variables used in the analysis of traditional industrial efficiency while conducting efficiency analysis focusing on the social performance by monetary value, which is considered the most important achievement of social enterprises. It is believed that it will contribute to research related to the environment creation and the requirements of each field in creating social values for social enterprises in the future.

• 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.