• Journal of Labour Economics
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• v.40 no.1
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• pp.69-97
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• 2017

This paper estimates the public and private sector wage gap trend from 2000 to 2014 using 'Korean Labor and Income Panel Study.' We account for unobserved fixed effect by using 1st differencing log wage in order to allow the gap to vary over time. Standard OLS estimates present the public sector wage is 10% higher than private sector on average. Moreover, the public sector wage premium displays the inverted V shape: sharply increasing up to 2006 and decreasing from 2007 to 2014. However, after controlling unobserved fixed effect, the public sector wage premium disappears and does not display the inverted V shape any more.

• Journal of Labour Economics
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• v.34 no.3
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• pp.119-139
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• 2011

Using a establishment-worker matched data, this paper estimates wage differentials between standard and non-standard workers. Unlike previous studies, we estimate a fixed-effect model for the tree-way error-components that control for both unobserved individual heterogeneities and unobserved firm heterogeneities. The estimation results show that standard workers earn 6.5~8.4% mire than non-standard workers. This wage premium is 30~40% of the wage differential estimated from the OLS model. The results implies that a large proportion of the wage differentials between standard and non standard workers can be explained by unobserved firm and individual characteristics.

• Korean Medical Education Review
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• v.12 no.1
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• pp.3-8
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• 2010

This study is designed to evaluate the effectiveness of teaching or studying programs, and thus to overcome the selectionbias in studies. Selection-bias derived from unobservable characteristics in the course of participants selection of the teaching or studying programs, in the case of cross-section data instrumental variable(IV) method and two stage least square estimation were suggested as an analysis tool. Panel data were analyzed by using both fixed effect in which individual effects are captured by intercept terms and random effect estimation where an unobserved effect can be characterized as being randomly drawn from a given distribution.

• Communications for Statistical Applications and Methods
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• v.29 no.3
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• pp.353-371
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• 2022

This paper analyzes death counts after World War II of several countries to identify and to compare their stochastic structures. The stochastic structures that this paper entertains are three structural time series models, a local level with a random walk model, a fixed local linear trend model and a local linear trend model. The structural time series models assume that a time series can be formulated directly with the unobserved components such as trend, slope, seasonal, cycle and daily effect. Random effect of each unobserved component is characterized by its own stochastic structure and a distribution of its irregular component. The structural time series models use the Kalman filter to estimate unknown parameters of a stochastic model, to predict future data, and to do filtering data. This paper identifies the best-fitted stochastic model for three types of death counts (Female, Male and Total) of each country. Two diagnostic procedures are used to check the validity of fitted models. Three criteria, AIC, BIC and SSPE are used to select the best-fitted valid stochastic model for each type of death counts of each country.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.853-861
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• 2020

The study aims to measure the productivity of the Saudi banking sector at the retail level using secondary data for 11 local banks from the period 2015-2019. The study uses an extended version of the Cobb-Douglas production function to account for the fact that as banks openup more retail branches, they will need to employ more labor. The extended Cobb-Douglas production function was estimated using the two-way fixed effect model to account for unobserved heterogeneity across Saudi banks resulting from differences in labor competencies and leadership style. Besides, the model accounts for unobserved heterogeneity among Saudi banks due to the advancement in electronic services over time. The results showed that labor, branches, customers' deposits, and fixed deposits have a positive effect on the total value of generated loans. Conversely, ATM has an insignificant effect on generated loans. The average scale elasticity shows that the Saudi banks at the retail level are operating under decreasing returns to scale. The average marginal rate of technical substitution shows that Saudi banks need at least one ATM to replace one unit of labor at the retail level while keeping the same level of output.

• Journal of Labour Economics
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• v.32 no.3
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• pp.1-26
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• 2009

Using panel data from the Korean Labor and Income Panel Study(KLlPS), we examine the wage differentials between standard and Don-standard workers. To control for unobserved individual heterogeneities, we estimate the fixed effect models. Our results show that the OLS estimates are upwardly biased. We also find that labor unions and firm size are important determinants of the wage differentials.

• Korean Journal of Social Welfare
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• v.63 no.4
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• pp.83-107
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• 2011

This study examines the duration dependence in the exit rate from National Basic Livelihood Protection Program(NBLP). If the length of time on welfare is negatively correlated with the exit rate after controlling for 'unobserved heterogeneity', the observed declining exit rates would provide evidence of true duration dependence. Data are drawn from Korean Welfare Panel study 2005~2008. A variety of discrete-time hazard models are estimated, including parametric/nonparametric hazard model, gamma frailty hazard model/mass point technique model. It is found that welfare dynamics in Korea does not show strong evidence of duration dependence after controlling for unobserved heterogeneity. All the models estimated show that this finding is quite robust. The observed declining exit rate is largely due to differences in the unobservable characteristics of recipients. Thus, the detrimental effect of the welfare on the preference and attitude among recipients is not likely to be strengthened as time on welfare increases.

• 한국노년학
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• v.40 no.1
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• pp.1-21
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• 2020

The purpose of this study is to examine that basic pension entitlement affects the subjective well-being(SWB) of the elderly. For controlling unobserved heterogeneity, we used fixed effects model for longitudinal data. The data used for this study is KLoSA from 2006 to 2016. The research results are as follows. SWB of non-basic pensioners was higher than for basic pension beneficiaries. Second, when the demographic variables were controlled, SWB of the basic pension recipients was higher then that of non-beneficiaries. Third, the factors affecting SWB were economic satisfaction, marital status, family financial support, employment status, subjective health status, daily life restrictions, gender, and age. Fourth, the effect of basic pension on SWB was positive at the lowest income quartile. The results of this study shows that the basic pension system has a positive effect on the SWB of elderly despite the low benefit level. Therefore, it is necessary to expand the basic pension system to solve poverty problems and improve the quality of life for the aged. Also, various aspects of social support for the low-income vulnerable elderly are needed. Lastly, It was suggested that the benefit level of the basic pension should be raised to have a substantial effect on the low-income class, which is a key policy subject.

• Journal of the Korean Statistical Society
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• v.28 no.2
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• pp.225-234
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• 1999

We consider the following semi-parametric non-linear mixed effect regression model : y\ulcorner=f($\chi$\ulcorner;$\beta$)+$\sigma$$\mu$($\chi$\ulcorner)+$\sigma$$\varepsilon$\ulcorner,i=1,…,n,y*=f($\chi$;$\beta$)+$\sigma$$\mu$($\chi$) where y'=(y\ulcorner,…,y\ulcorner) is a vector of n observations, y* is an unobserved new random variable of interest, f($\chi$;$\beta$) represents fixed effect of known functional form containing unknown parameter vector $\beta$\ulcorner=($\beta$$_1$,…,$\beta$\ulcorner), $\mu$($\chi$) is a random function of mean zero and the known covariance function r(.,.), $\varepsilon$'=($\varepsilon$$_1$,…,$\varepsilon$\ulcorner) is the set of uncorrelated measurement errors with zero mean and unit variance and $\sigma$ is an unknown dispersion(scale) parameter. On the basis of finite-sample, small-dispersion asymptotic framework, we derive an absolute lower bound for the asymptotic mean squared errors of prediction(AMSEP) of the regular-consistent non-linear predictors of the new random variable of interest y*. Then we construct an optimal predictor of y* which attains the lower bound irrespective of types of distributions of random effect $\mu$(.) and measurement errors $\varepsilon$.

• 한국사회정책
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• v.23 no.1
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• pp.95-123
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• 2016

As Korean society grows rapidly older, a systematic analysis of the determinants of labor supply behavior among the elderly becomes a prerequisite for designing more effective senior employment policies and income security regime for the elderly. Literatures review shows that a majority of previous researches have been ignoring the problem of "endogenous predictor" especially when it comes to the estimation of the effects of the two key variables, education and non-labor income, on labor supply decisions among older people. They have failed to take into consideration the unobserved heterogeneities which might affect both labor supply decisions of the elderly and their levels of education and non-labor income, which means, according to some econometric literatures, that the estimated coefficients of the two predictors can be inconsistent. The paper tries to redress the endogeneity problem by employing a panel logit model with data from the 1st. to 4th. wave of the KLoSA(Korean Longitudinal Survey of Ageing) to estimate the effects of key predictors on the probability of getting jobs among older people(ages of 60 or older). Both a random effects and a fixed effects model reaffirms that non-labor income has a negative effect on the chances of being employed. And a random effects model shows that the effect of education is also negative, as has frequently been reported by previous studies. That means the effects of education and non-labor income on elderly employment remain negative after the effect of unobserved heterogeneities is controled for and the problem of endogenous predictors is redressed through an appropriate panel data analysis. These findings mean, in turn, that when Korean baby-boomers, who had acquired an unprecedentedly higher level of education and were expected to enjoy ever-larger amount of non-labor income than their preceding generations, retires in near future, their incentives to work will become much weaker and the lack of labor-force and the burden of financing increased public pension expenditure will become more troublesome. The paper concludes with recommending some policy initiatives helpful to solve these expected problems.