• The Korean Journal of Applied Statistics
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• v.33 no.2
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• pp.123-136
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• 2020

It is common to encounter correlated multiple outcomes measured on the same subject in various research fields. In developmental toxicity studies, presence of malformed pups and fetal weight are measured on the pregnant dams exposed to different levels of a toxic substance. Joint analysis of such two outcomes can result in more efficient inferences than separate models for each outcome. Most methods for joint modeling assume a normal distribution as random effects. However, in developmental toxicity studies, the response distributions may change irregularly in location and shape as the level of toxic substance changes, which may not be captured by a normal random effects model. Motivated by applications in developmental toxicity studies, we propose a Bayesian joint model for binary and continuous outcomes. In our model, we incorporate a skewed logit model for the binary outcome to allow the response distributions to have flexibly in both symmetric and asymmetric shapes on the toxic levels. We apply our proposed method to data from a developmental toxicity study of diethylhexyl phthalate.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1116-1123
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• 2006

The methodological framework proposed in this paper addresses the strength of the applied Bass model by Mahajan and Muller(1996) that it reflects the substitution of next generations among products. Also this paper is to estimate and analyze the forecast of demand for products that do not exist in the marketplace. We forecast the sales of digital TV using estimated market share and data obtained by the face to face Interview. In this research, we use two methods to analyze the demand for Digital TV that are the forecasting the Demand for the Substitution and binary logit analysis. The logit analysis is to estimate the decisive factor of purchasing digital TV. The decisive factors are composed of purchasing plan, region, gender, TV price, contents, coverage, income, age, and TV program. We apply the model to South Korea's market for digital TV. The results show that (1) Income, region and TV price play a prominent part which is the decisive factor of purchasing digital TV. (2) We forecaste the demand of digital TV that will be demanded about 18 millions TVs in 2015

• The Korean Journal of Applied Statistics
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• v.21 no.2
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• pp.291-299
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• 2008

This paper discusses model building for repeated binary response data with different time-dependent covariates each occasion. Since repeated measurements data are having correlated structure, weighed least squares(WLS) methodology is applied. Repeated measures designs are usually having different sizes of experimental units like split-plot designs. However repeated measures designs differ from split-plot designs in that the levels of one or more factors cannot be randomly assigned to one or more of the sizes of experimental units in the experiment. In this case, the levels of time cannot be assigned at random to the time intervals. Because of this nonrandom assignment, the errors corresponding to the respective experimental units may have a covariance matrix. So, the estimates of effects included in a suggested logit model are obtained by using covariance structures.

• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.360-365
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• 2016

The purpose of this study is to provide the basic information for the early enforcement and extension of the improvement project of management scale of private forest land by understanding the characteristics of forest owners, who have an influence on the participation of the project as one of the private forest management vitalization plans. To achieve this goal, a questionnaire survey targeting 373 forest owners was conducted and analyzed by Binary-Logistic Regression. The variables for binary-logistic regression included gender, age, academic ability, occupation, income, residence, purpose of forest ownership, and status of cooperative membership. As a result of the analysis, 267 forest owners (71.6%) of total 373 forest owners have the intention to participate in the scaling project for private forest management. The rest of forest owners (106 forest owners, 28.4%) would not be willing to participate in the project. As a result of binary-logistic regression, the most important variables, which have an impact on the participation of private forest management scale improvement project, are age, job and forest own purpose.

• International Journal of Highway Engineering
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• v.9 no.1 s.31
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• pp.17-27
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• 2007

Since early 1990s, several developed countries have applied the Electronic Toll Collection System (ETCS) to toll roads in order to solve traffic congestion and delay problems at toll plazas. For the successful operation of the ETCS, it is important to correctly forecast the ETCS using rate. In this study, it was conceived to develop a sophisticated demand forecasting model of the ETCS for toll roads in Changwon City The Binary Logit and neural network models were tested for the model considering 11 explaining variables. The best results in prediction accuracy and goodness-of-fit were obtained on the neural network model. However, because of the difficulty in predicting the 11 variables and its fitness in wide range, the Binary Logit model which considers three policy variables only is recommended as the model to forecast the ETCS using rate.

• Journal of Agricultural Extension & Community Development
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• v.27 no.2
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• pp.75-87
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• 2020

The purpose of this study is to investigate the location characteristics of the rice paddy fields and to predict shrinking areas of them. The study area is in South Korea nationwide, and a 300×300m raster level is adopted as a spatial analysis unit. The binary logit model and spatial simulation model are employed for the analyses. As a result, population, industry, climate and nature, and accessibility play a significant role in determining rice paddy fields' locations. It is predicted that the shrinking rate will be high in Gangwon-do, Gyeongsangbuk-do, and Gyeongsangnam-do until 2027. The hot spots are intensively shaped in the inland of Gangwon-do, eastern parts of Gyeonggi-do, and the borders of Gyeongsangnam-do and Jeollabuk-do between Charyeong and Sobaek mountain ranges. Using Gimcheon-si as an example, the study suggests fundamental policy implications for taking advantage of the simulation results from the lens of local agriculture. Several policy measures are proposed for improving management strategies for the rice paddy fields in the long run.

• Proceedings of the Korean Association for Survey Research Conference
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• 2001.04a
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• pp.83-107
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• 2001

The contingent valuation method used survey questions to elicit people's preferences for public goods by finding out what they would be willing to pay for specified improvement in them. The method is thus aimed at eliciting their willingness to pay in money amounts. It circumvents the absence of markets for public goods by presenting consumers with hypothetical markets in which they have the opportunities to buy the good in question. The hypothetical markets may be modeled after either a private goods market or a political market. Respondents are presented with material, often in the course of a personal interview conducted face to face. An on-site survey was conducted to 1107 randomly selected P-mountain users using a dichotomous choice questionnaire for the contingent valuation method. Seventeen different bid sets were chosen ranging from the lowest bid of 300won to the highest bid of 2,100won to elicit a reasonable entrance fee in the suggested bid had been determined, and the expected value of willingness to pay was estimated using binary-logit model. The average public value of P-mountain per individual user was estimated to be 1,055.92won∼1,995.61won according to the binary-logit model. The economic value of this P-mountain which includes both use value and existence value can be determined by aggregating the average value giving total willingness to pay for the entire population, in this case 5.491 billion ∼ 10.377 billion.

• The Korean Journal of Applied Statistics
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• v.18 no.1
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• pp.173-182
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• 2005

A Bayesian threshold model is considered to analyze binary or ordered categorical traits. Gibbs sampler for making full Bayesian inferences about the category probability as well as the regression coefficients is described. The model can be regarded as an alternative to the ordered logit regression model. Numerical examples are shown to demonstrate the efficiency of the model.

• Communications for Statistical Applications and Methods
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• v.12 no.2
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• pp.313-322
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• 2005

In this paper, we discuss suppression for logistic regression model. Suppression for linear regression model was defined as the relationship among sums of squared for regression as well as correlation coefficients of. variables. Since it is not common to obtain simple correlation coefficient for binary response variable of logistic model, we consider cumulative logistic models with multinomial and ordinal response variables rather than usual logistic model. As number of category of a response variable for the cumulative logistic model gets collapsed into binary, it is found that suppressions for these logistic models are changed. These suppression results for cumulative logistic models are discussed and compared with those of linear model.

• Journal of Korean Society of Transportation
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• v.24 no.6 s.92
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• pp.21-32
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• 2006

The purpose of this study is to determine the economical standard for road signs by verifying the difference in driver's legibility time with respect to the spacing of letters on the toad signs. Laboratory simulations were conducted to confirm the difference in legibility time for six target signs of different spacing. Also. a binary logit model was used to find the main factors, which could lower the rate if misreading. This model involves not only a simple enlargement of signs but also a suitable match of letters and signs along with the optimal spacing of the text letters on the road signs to increase the legibility of the sign. The result of this study verified the importance of spacing in road signs and Proved itself to be an effective method to determine the future standard for the road signs.