• The Korean Journal of Applied Statistics
• /
• v.31 no.6
• /
• pp.733-749
• /
• 2018

Sample selection arises as a result of the partial observability of the outcome of interest in a study. Heckman introduced a sample selection model to analyze such data and proposed a full maximum likelihood estimation method under the assumption of normality. Recently sample selection models for binomial and Poisson response variables have been proposed. Based on the theory of symmetry-modulated distribution, we extend these to a model for overdispersed count data. This type of data with no sample selection is often modeled using negative binomial distribution. Hence we propose a sample selection model for overdispersed count data using the negative binomial distribution. A real data application is employed. Simulation studies reveal that our estimation method based on profile log-likelihood is stable.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.42 no.2
• /
• pp.323-330
• /
• 2017

The millimeter wave band is in the extremely high frequency band whose frequency and wavelength are 30-300GHz and 10-1mm respectively. When the obstacles block the propagation path which is not Line-of-Sight (LoS), due to a high propagation loss, it is hard to receive a signal in the millimeter wave band. Therefore When the path loss is measured in the millimeter wave band, the signal which is not distinguished from the noise is observed. Consequently, the path loss data which is limited in certain value is observed in the high propagation loss environment. If the original least square is implemented without taking the limitation of certain value into account, the path loss exponent may be underestimated. In this paper, the performance of Tobit Maximum Likelihood Estimation, Heckman Two-stage Model and Truncation Regression Model which can estimate properly in the censoring or truncated environments are compared.

• Journal of Labour Economics
• /
• v.40 no.1
• /
• pp.37-68
• /
• 2017

This study analyzes the relationship between household debts and married female's labor supply. For doing this we construct effective interest rate faced by each household using interest paid amount and household financial debt amount. The effective interests rate for the households which have no financial debt are estimated by Heckman Selection model. The estimation results show that the increase in effective interest rate has led to the expansion of married women's the labor market participation. This suggests a possibility that negative scenarios resulting from an increase in interest rate can be partially offset by an increase in household labor supply and a rise in labor income.

• Journal of Labour Economics
• /
• v.23 no.2
• /
• pp.127-151
• /
• 2000

The empirical study that used the logit model and the Heckman's selection bias model based upon 'Korea Labor & Income Panel Study' shows that the experience of job training has a positive effect on the probability of employment, as well as on the wage increase. The analysis also sheds light on the effect on employment with wage workers who experienced job training. When the discouraged unemployed are not classified as labor force participants, that is the unemployed, and the industrial dummy variables are excluded, logit estimation shows that training program in the public sector, not in the private sector, significantly increases their employment probability. However when these same workers are classified as the unemployed and the industrial dummies are included, logit estimation shows that public and private training programs has no effect on their employability.

• International Journal of Human Ecology
• /
• v.4 no.2
• /
• pp.77-87
• /
• 2003

This paper tried to construct statistical and econometric models on the basis of economic theory in order to discuss the issue of statistical efficiency and unbiasedness including the sample selection bias correcting problem. Comparative analytical tool were one stage Tobit of Maximum Likelihood estimation and Heckman's two-step Tobit of Ordinary Least Squares. The results showed that the adequacy of model for the analysis on demand and choice, we believe that there is no big difference in explanatory variables between the first selection model and the second linear probability model. Since the Lambda, the self- selectivity correction factor, in the Type II Tobit is not statistically significant, there is no self-selectivity in the Type II Tobit model, indicating that Type I Tobit model would give us better explanation in the demand for and choice which is less complicated statistical method rather than type II model.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.9
• /
• pp.427-434
• /
• 2018

As noted by Pavitt (1984) and Malerbar (2002), previous studies have focused on identifying differences in industry characteristics between the machinery industry and other manufacturing industries. This study considered quantitative and qualitative aspects of performance of product innovation in analyzing what factors determine those outcomes. In particular, this study examined stepwise selection processes embedded in innovation activities by applying a hurdle negative binomial model as well as the Heckman two-step selection model. Results show that factors affecting performance improvement and patents differ, and the threshold effect and the intensity effect of innovation were also distinguished. These results imply that the R&D capability should be enhanced and external innovation is required to be effectively embodied in the organization. Furthermore, motivating employees plays a pivotal role in this technology and skill-intensive sector.

• The Journal of Asian Finance, Economics and Business
• /
• v.6 no.2
• /
• pp.75-82
• /
• 2019

The paper aims to investigate the impacts of long-term savings motives on fostering household participation and contribution to savings mechanisms in rural Vietnam. The paper is organized in five parts: introduction, data description, methodology, empirical results, and conclusion. The quantitative methodology is employed and three simultaneous estimation methods, including instrumental variable model, two-step model, and Heckman model are used to test these impacts as well as the robustness of results. In each model, the paper examines the impacts of independent factors on both household participation and household contribution to savings mechanisms. Two sets of independent variables: long-term savings motives (profit-making investment, accumulation for big expenditure, providing for old age, and cost of educations) and control variables (dependency rate, number of people in household, and household wealth) are in each model. A set of dataset of 2,314 households for analysis is obtained from household survey in rural Vietnam. Robust statistical findings indicate that profit-making investment emerged to be the strongest motive fostering household participation to savings mechanisms while other long-term savings motives have little or no impact on fostering household participation to savings mechanisms. In addition, education investment encourages household contribution to savings mechanisms in rural Vietnam.

• Journal of Korean Society of Rural Planning
• /
• v.25 no.3
• /
• pp.29-36
• /
• 2019

The purpose of this study was to analyze affecting factors to consider and make decision on the urban-to-rural migrants using survey data. In the consideration model of urban-to-rural migrants, it was found that the more interest in "urban-to-rural migrants concern" was, the higher probability to consider about urban-to-rural migrants. The lower the age and income level, the higher probability to consider about the urban-to-rural migrants. In the decision making model of urban-to-rural migrants, the more interest in "urban-to-rural migrants concern" was, the higher probability to decision making of urban-to-rural migrants. The higher of stable pension income and the lower of the expected living cost, the higher probability of decision on urban-to-rural migrants. The results of this analysis show that it is necessary to continuous education to increase "interests and information about rural areas", and A number of safeguards are needed to ensure stable income after urban-to-rural migrants to increase the population of the urban-to-rural migrants.

• Journal of Labour Economics
• /
• v.32 no.1
• /
• pp.57-75
• /
• 2009

This paper provides empirical evidence on the impact of SCHIP (The State Children's Health Insurance Program) on single mothers' working decisions using recent CPS (Current Population Survey) data during 1999-2005. SCHIP are found to have a significant positive impact on hours-worked decision.

• International Journal of Human Ecology
• /
• v.9 no.1
• /
• pp.81-95
• /
• 2008

This paper examined the impact of psychological characteristics of consumers on household debt decisions. With the use of the Heckit models (the traditional approach to the selection problem) this study undertook an empirical study of the influence of a wide range of factors on financial decisions. This study used U.S. household-level data that offers detailed information on household debt, expectations about future income, expectations about future economic conditions, the amount of financial risk the respondent was willing to take, and the amount of time allotted for planning family savings and spending. This study showed that respondents with both substantial financial risk tolerance and positive expectations about future income were likely to have larger household debt showing that researchers and policy-makers need to consider consumer sentiment and preference measures in modeling behavior in credit markets. Additional results showed that household debt is significantly related to two key economic variables: income and net worth.