• 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.

• Communications for Statistical Applications and Methods
• /
• v.20 no.1
• /
• pp.77-84
• /
• 2013

This paper deals with the relative efficiency of two kernel estimators $\hat{f}_n$ and $\hat{g}_n$ by using spherical data, as proposed by Park (2012), and Bai et al. (1988), respectively. For this, we suggest the computing flows for the relative efficiency on the 2-dimensional unit sphere. An evaluation procedure between two estimators (given the same kernels) is also illustrated through the observed data on normals to the orbital planes of long-period comets.

• Journal of Society of Preventive Korean Medicine
• /
• v.17 no.3
• /
• pp.103-114
• /
• 2013

Objectives : This study aimed to analyze the management efficiency of Korean Medicine hospitals for recent 10 years(2001~2010) using the Data Envelop Analysis(DEA) model. Methods : We collected the management data of 23 Korean Medicine hospitals for DEA model from the Korean Oriental Medicine Hospitals' Association (KOMHA). Input variables of DEA model are numbers of beds, numbers of doctors, numbers of nurses and numbers of other staffs of each Korean Medicine hospitals. Output variables are numbers of inpatients and numbers of outpatients of each Korean Medicine hospitals. Based on the DEA model, we calculated the efficiency score of each Korean Medicine hospital and compared it by hospital's ownership, location, and size. Results : Average DEA efficiency scores of Korean Medicine hospitals by year ranged from 0.86 to 0.92. Private owned hospitals showed higher efficiency scores than the university affiliated hospitals with statistical significance (p=0.001). And Korean Medicine hospitals located in capital region of Korea(Seoul City, Incheon City, Gyeonggi-do) and the rest Korean Medicine hospitals did not show statistical difference (p=0.516). Lastly, Korean Medicine hospitals with different size did not show statistical difference in management efficiency (p=0.499). Conclusion : We have found that Korean Medicine hospitals management efficiency have not changed throughout 10 years, and that different ownership forms of Korean Medicine hospital show statistical difference in management efficiency while location, and size do not.

• Journal of Digital Convergence
• /
• v.12 no.8
• /
• pp.139-146
• /
• 2014

We investigated the relative efficiency and statistical analysis of Kimchi-related manufactures in Jeollabuk-do for their management efficiency and improvement plans. We used data enveloped analysis (DEA) for the relative efficiency, and principal component analysis (PCA) and t-test for the statistical analysis. We analyzed 34 DMUs among 67 DMUs located in Jeollabuk-do. The results were as follows; the statistical efficiency, pure statistical efficiency, scale efficiency for 34 DMUs were 0.653, 0.761, and 0.863, respectively. The correlated component regression (CCR) showed that DMUs above efficiency 1 were 61.5% among -si (urban area), and 23.8% among -gun (rural area), respectively. However, there were not the significant differences of and BCC, CCR, and scale efficiency between urban area and rural area. This study will be useful for local industry's promotion by providing the information on Kimchi-related manufactures.

• Proceedings of the Korean Statistical Society Conference
• /
• 2003.10a
• /
• pp.201-205
• /
• 2003

We show how some probability nonreplacement sampling designs can be implemented using nonlinear programming, The efficiency of the proposed approach is compared with selected probability sampling schemes in the literature. The approach is simple to use and appears to have reasonable variance.

• Communications for Statistical Applications and Methods
• /
• v.15 no.6
• /
• pp.947-957
• /
• 2008

In this paper, we consider the c-sample location problem for ordered alternatives using median ranked ordering-set samples(MROSS). We propose the test statistic using the median of samples that have the same ranked order in each cycle of ranted ordering-set sample(ROSS). We obtain the asymptotic property of the proposed test statistic and Pitman efficiency with respect to other test statistic. In simulation study, our proposed test statistic has good powers for some underlying distributions we consider.

• Journal of the Korean Statistical Society
• /
• v.30 no.4
• /
• pp.551-561
• /
• 2001

This paper deals with the asymptotic properties for statistical inferences of the parameters in nonlinear regression models. As an optimal criterion for robust estimators of the regression parameters, the regression quantile method is proposed. This paper defines the regression quintile estimators in the nonlinear models and provides simple and practical sufficient conditions for the asymptotic normality of the proposed estimators when the parameter space is compact. The efficiency of the proposed estimator is especially well compared with least squares estimator, least absolute deviation estimator under asymmetric error distribution.

• Journal of the Korea Management Engineers Society
• /
• v.23 no.4
• /
• pp.73-86
• /
• 2018

Most electric products produced during the manufacturing process are produced after design and mass production under a given control standard. In particular, the development phase should present the criteria for the production process by setting appropriate limits based on the performance being targeted. Even if the standard of performance is set considering the performance of the process, measuring the performance of the product after actual production results will cause nonconformities with the expected results. Among the performance of electrical products, Energy standards represented by energy consumption efficiency continue to be of importance, and are mandatory standards that correspond to national standards in most countries. Therefore, statistical quality control of these standards shall basically have a large number of test equipment for each product, ensure sufficient test time and continuous sampling of product samples. In the end, companies that produce and sell electric appliances are striving to control mass production at a great cost, but this is not acceptable. This study presents basic characteristics of the energy efficiency of electrical products and proposes and conducts a case study on statistical production control methods for performance variation across products under the standards about domestic and international regulations.

• Journal of the Korean Statistical Society
• /
• v.30 no.3
• /
• pp.419-433
• /
• 2001

In this paper we introduce a method of improving efficiency of the moment estimator of Dekkers, Einmahl and de Haan(1989) for the extreme value index $\beta$. a new estimator of $\beta$ is proposed by adding the third moment ot the original moment estimator which is composed of the first two moments of the log-transformed sample data. We establish asymptotic normality of the new estimator and examine and adaptive procedure for the new estimator. The resulting adaptive estimator proves to be asymptotically better than the moment estimator particularly for $\beta$<0.

• Journal of the Korean Statistical Society
• /
• v.25 no.1
• /
• pp.95-110
• /
• 1996

We consider the question of efficiency of the Bayes sequential procedure with respect to the optimal fixed sample size Bayes procedure in a simple vs. simple testing problem for data coming from a general nonregular density b(.theta.)h(x)l(x < .theta.). Efficiency is defined in two different ways in these caiculations. Also, the minimax sequential risk (and minimax sequential stratage) is studied as a function of the cost of sampling.