• Title/Summary/Keyword: latent class 모델

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Analysis of the Effect in Mathematics Teachers Beliefs on their Students Beliefs by Latent Class Regression Model (잠재집단회귀모델(LCRM)을 통한 학생의 수학적 신념에 대한 교사의 수학적 신념 영향분석)

  • Kang, Sung Kwon;Hong, Jin-Kon
    • Communications of Mathematical Education
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    • v.34 no.4
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    • pp.485-506
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    • 2020
  • The purpose of this study is to analyze of the effect in Mathematics Teachers beliefs on their students beliefs by Latent Class Regression Model (LCRM). For this analysis, the study used the findings and surveys of Kang, Hong (2020) who developed a belief profile by analyzing the mathematical beliefs of 60 high school teachers and 1,850 second-year high school students learning from them through the Latent Class Analysis (LCA). As a result It was observed that 'Nature of Mathematics', 'Mathematic Teaching' and 'Mathematical Ability' of mathematics teachers beliefs influence the mathematical beliefs of students. The teacher's belief of 'Nature of Mathematics' statistically significant effects on students' beliefs in 'School Mathematics', 'Problem Solving', 'Mathematics Learning'. The teacher's belief of 'Teaching Mathematics', 'Mathematical Ability' statistically significant effects on students' beliefs in 'School Mathematics', 'Problem Solving', 'Self-Concept'. The results of this study can give a preview of the phenomenon in which teacher's mathematical beliefs are reproduced into student's mathematical beliefs. In addition, the results of observation of this study can be used to the contents that can achieve the purpose of reorientation for mathematics teachers.

Bayesian Clustering of Prostate Cancer Patients by Using a Latent Class Poisson Model (잠재그룹 포아송 모형을 이용한 전립선암 환자의 베이지안 그룹화)

  • Oh Man-Suk
    • The Korean Journal of Applied Statistics
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    • v.18 no.1
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    • pp.1-13
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    • 2005
  • Latent Class model has been considered recently by many researchers and practitioners as a tool for identifying heterogeneous segments or groups in a population, and grouping objects into the segments. In this paper we consider data on prostate cancer patients from Korean National Cancer Institute and propose a method for grouping prostate cancer patients by using latent class Poisson model. A Bayesian approach equipped with a Markov chain Monte Carlo method is used to overcome the limit of classical likelihood approaches. Advantages of the proposed Bayesian method are easy estimation of parameters with their standard errors, segmentation of objects into groups, and provision of uncertainty measures for the segmentation. In addition, we provide a method to determine an appropriate number of segments for the given data so that the method automatically chooses the number of segments and partitions objects into heterogeneous segments.

Modeling the Effect of Consideration Set-Based Reference Price: Empirical Bayes & Latent Class Approach (고려상품군을 반영한 준거가격효과의 모형화: Empirical Bayes & Latent Class Approach)

  • Chang, Kwangpil
    • Asia Marketing Journal
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    • v.8 no.1
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    • pp.1-17
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    • 2006
  • A couple of previous studies have warned against the use of homogeneous choice models in assessing the effect of reference price since unaccounted for response heterogeneity may result in spurious reference price effects(Chang, Siddarth and Weinberg 1999; Bell and Lattin 2000). According to Meyer and Kahn(1991), not accounting for consideration set heterogeneity may also bias the effect parameters in the choice model. Therefore, failure to account for these two sources of bias, in fact, have cast doubt on the empirical support for reference price effects in general. In view of aforementioned potential sources of bias, the author investigates the robustness of loss aversion effect in the reference-dependent model after accounting for heterogeneity in response as well as consideration set. The proposed model defines individual household's consideration set based on the posterior distribution of preference obtained from the Empirical Bayes approach. In addition, the same posterior distribution is used to form household-specific reference prices. Response heterogeneity correction is carried out via the Latent Class approach. The proposed model outperforms the Reference-Dependent model that includes the reference price measure most often employed in the previous studies. This implies that as a way of simplifying decision task, consumers restrict their consideration set to a subset of available brands not only in making a brand choice but also in forming reference prices.

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Identifying Latent Classes of Risk Factors for Coronary Artery Disease (잠재계층분석을 활용한 관상동맥질환 위험요인의 유형화)

  • Ju, Eunsil;Choi, JiSun
    • Journal of Korean Academy of Nursing
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    • v.47 no.6
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    • pp.817-827
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    • 2017
  • Purpose: This study aimed to identify latent classes based on major modifiable risk factors for coronary artery disease. Methods: This was a secondary analysis using data from the electronic medical records of 2,022 patients, who were newly diagnosed with coronary artery disease at a university medical center, from January 2010 to December 2015. Data were analyzed using SPSS version 20.0 for descriptive analysis and Mplus version 7.4 for latent class analysis. Results: Four latent classes of risk factors for coronary artery disease were identified in the final model: 'smoking-drinking', 'high-risk for dyslipidemia', 'high-risk for metabolic syndrome', and 'high-risk for diabetes and malnutrition'. The likelihood of these latent classes varied significantly based on socio-demographic characteristics, including age, gender, educational level, and occupation. Conclusion: The results showed significant heterogeneity in the pattern of risk factors for coronary artery disease. These findings provide helpful data to develop intervention strategies for the effective prevention of coronary artery disease. Specific characteristics depending on the subpopulation should be considered during the development of interventions.

A Spatial Pyramid Matching LDA Model using Sparse Coding for Classification of Sports Scene Images (스포츠 이미지 분류를 위한 희소 부호화 기법을 이용한 공간 피라미드 매칭 LDA 모델)

  • Jeon, Jin;Kim, Munchurl
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2016.06a
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    • pp.35-36
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    • 2016
  • 본 논문에서는 기존 Bag-of-Visual words (BoW) 접근법에서 반영하지 못한 이미지의 공간 정보를 활용하기 위해서 Spatial Pyramid Matching (SPM) 기법을 Latent Dirichlet Allocation (LDA) 모델에 결합하여 이미지를 분류하는 모델을 제안한다. BoW 접근법은 이미지 패치를 시각적 단어로 변환하여 시각적 단어의 분포로 이미지를 표현하는 기법이며, 기존의 방식이 이미지 패치의 위치정보를 활용하지 못하는 점을 극복하기 위하여 SPM 기법을 도입하는 연구가 진행되어 왔다. 또한 이미지 패치를 정확하게 표현하기 위해서 벡터 양자화 대신 희소 부호화 기법을 이용하여 이미지 패치를 시각적 단어로 변환하였다. 제안하는 모델은 BoW 접근법을 기반으로 위치정보를 활용하는 SPM 을 LDA 모델에 적용하여 시각적 단어의 토픽을 추론함과 동시에 multi-class SVM 분류기를 이용하여 이미지를 분류한다. UIUC 스포츠 데이터를 이용하여 제안하는 모델의 분류 성능을 검증하였다.

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희소 부호화 기법과 토픽 모델링을 통한 이미지 분류 모델

  • Jeon, Jin;Kim, Munchurl
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2015.07a
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    • pp.49-50
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    • 2015
  • 본 논문에서는 이미지를 시각적 단어로 표현하여 분석하는 기법인 bag-of-visual words (BoW) 모델을 기반으로 latent dirichlet allocation (LDA) 모델을 결합하여 시각적 단어의 구조를 파악하여 이미지를 분류할 수 있는 모델을 제안한다. 우선 이미지를 시각적 단어로 기존의 방법보다 정확하게 표현하기 위해서 희소 부호화(sparse coding) 기법을 적용한다. 기존의 BoW 모델은 하나의 이미지 패치를 하나의 단어로 표현하였지만, 희소 부호화 기법을 통해 하나의 이미지 패치를 여러 개의 단어로 표현할 수 있다. 제안하는 모델을 이용하여 이미지를 분류하기 위해서 분류 성능 측정에 많이 쓰이는 multi-class SVM 기법을 이용한다. UIUC 스포츠 데이터를 이용한 성능 측정을 통해 제안한 기법의 클래스 분류 성능을 검증하였다.

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Longitudinal Patterns of Stages of Changes in Smoking Behaviors among Korean Adult Smokers: Applying the Transtheoretical Model of Change (범이론적 모델에 기반을 둔 흡연자의 금연행동 변화단계에 대한 탐색적 연구)

  • Park, Hyunyong;Jun, Jina;Sohn, Sunju
    • Korean Journal of Social Welfare Studies
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    • v.49 no.1
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    • pp.5-28
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    • 2018
  • Smoking is one of the important public health concerns because it is preventable causes regarding individuals' negative health consequences and increased social and economic cost. However, few studies have examined longitudinal patterns of stages of changes(SOC) in smoking behaviors among the general population. The purpose of the study is to explore the latent patterns of SOC over time among Korean adult smokers using the 2008-2016 Korea Welfare Panel Study. A repeated measure latent class analysis is employed in the present study. The finding of the present study are as follows: First, four latent groups were identified: (1) action/maintenance stage(33.6%), (2) contemplation/preparation to action/maintenance stage(14.8%), (3) continuously contemplation/preparation stage(29.6%), and (4) continuously pre-contemplation stage(22.1%). Second, the results of a multinomial logistic regression found that socio-demographic and clinical characteristics were associated with the identified longitudinal patterns of smoking behaviors. Compared to a continuously pre-contemplation stage, higher levels of depressive symptoms and drinking behavior were associated with increased odds of being in action/maintenance stage. The findings of the present study highlight that a tailored intervention is needed for individuals with continuously pre-contemplation stage and contemplation stage.

Label Embedding for Improving Classification Accuracy UsingAutoEncoderwithSkip-Connections (다중 레이블 분류의 정확도 향상을 위한 스킵 연결 오토인코더 기반 레이블 임베딩 방법론)

  • Kim, Museong;Kim, Namgyu
    • Journal of Intelligence and Information Systems
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    • v.27 no.3
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    • pp.175-197
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    • 2021
  • Recently, with the development of deep learning technology, research on unstructured data analysis is being actively conducted, and it is showing remarkable results in various fields such as classification, summary, and generation. Among various text analysis fields, text classification is the most widely used technology in academia and industry. Text classification includes binary class classification with one label among two classes, multi-class classification with one label among several classes, and multi-label classification with multiple labels among several classes. In particular, multi-label classification requires a different training method from binary class classification and multi-class classification because of the characteristic of having multiple labels. In addition, since the number of labels to be predicted increases as the number of labels and classes increases, there is a limitation in that performance improvement is difficult due to an increase in prediction difficulty. To overcome these limitations, (i) compressing the initially given high-dimensional label space into a low-dimensional latent label space, (ii) after performing training to predict the compressed label, (iii) restoring the predicted label to the high-dimensional original label space, research on label embedding is being actively conducted. Typical label embedding techniques include Principal Label Space Transformation (PLST), Multi-Label Classification via Boolean Matrix Decomposition (MLC-BMaD), and Bayesian Multi-Label Compressed Sensing (BML-CS). However, since these techniques consider only the linear relationship between labels or compress the labels by random transformation, it is difficult to understand the non-linear relationship between labels, so there is a limitation in that it is not possible to create a latent label space sufficiently containing the information of the original label. Recently, there have been increasing attempts to improve performance by applying deep learning technology to label embedding. Label embedding using an autoencoder, a deep learning model that is effective for data compression and restoration, is representative. However, the traditional autoencoder-based label embedding has a limitation in that a large amount of information loss occurs when compressing a high-dimensional label space having a myriad of classes into a low-dimensional latent label space. This can be found in the gradient loss problem that occurs in the backpropagation process of learning. To solve this problem, skip connection was devised, and by adding the input of the layer to the output to prevent gradient loss during backpropagation, efficient learning is possible even when the layer is deep. Skip connection is mainly used for image feature extraction in convolutional neural networks, but studies using skip connection in autoencoder or label embedding process are still lacking. Therefore, in this study, we propose an autoencoder-based label embedding methodology in which skip connections are added to each of the encoder and decoder to form a low-dimensional latent label space that reflects the information of the high-dimensional label space well. In addition, the proposed methodology was applied to actual paper keywords to derive the high-dimensional keyword label space and the low-dimensional latent label space. Using this, we conducted an experiment to predict the compressed keyword vector existing in the latent label space from the paper abstract and to evaluate the multi-label classification by restoring the predicted keyword vector back to the original label space. As a result, the accuracy, precision, recall, and F1 score used as performance indicators showed far superior performance in multi-label classification based on the proposed methodology compared to traditional multi-label classification methods. This can be seen that the low-dimensional latent label space derived through the proposed methodology well reflected the information of the high-dimensional label space, which ultimately led to the improvement of the performance of the multi-label classification itself. In addition, the utility of the proposed methodology was identified by comparing the performance of the proposed methodology according to the domain characteristics and the number of dimensions of the latent label space.

Online anomaly detection algorithm based on deep support vector data description using incremental centroid update (점진적 중심 갱신을 이용한 deep support vector data description 기반의 온라인 비정상 탐지 알고리즘)

  • Lee, Kibae;Ko, Guhn Hyeok;Lee, Chong Hyun
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.2
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    • pp.199-209
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    • 2022
  • Typical anomaly detection algorithms are trained by using prior data. Thus the batch learning based algorithms cause inevitable performance degradation when characteristics of newly incoming normal data change over time. We propose an online anomaly detection algorithm which can consider the gradual characteristic changes of incoming normal data. The proposed algorithm based on one-class classification model includes both offline and online learning procedures. In offline learning procedure, the algorithm learns the prior data to be close to centroid of the latent space and then updates the centroid of the latent space incrementally by new incoming data. In the online learning, the algorithm continues learning by using the updated centroid. Through experiments using public underwater acoustic data, the proposed online anomaly detection algorithm takes only approximately 2 % additional learning time for the incremental centroid update and learning. Nevertheless, the proposed algorithm shows 19.10 % improvement in Area Under the receiver operating characteristic Curve (AUC) performance compared to the offline learning model when new incoming normal data comes.

Identifying latent classes about the changing trajectories of child maltreatment by child developmental period (아동발달시기별 아동학대 변화궤적 유형 비교 연구)

  • Han, Jihyeon;Choi, Okchae
    • Journal of the Korean Society of Child Welfare
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    • no.59
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    • pp.183-208
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    • 2017
  • The purpose of this study was to identify groups depending on the change trajectory of child maltreatment in childhood and early adolescence. For this study, the data from waves two through six (2011-2015) of the Korean Children and Youth Panel Survey (KCYPS) were used. Participants included first-grade (n=2,300) and fourth-grade (n=2,325) elementary school students. A latent class growth model (LCGM) using Mplus 7.21 was adopted to classify the types of developmental trajectories of child maltreatment. The main results were as follows: First, in physical abuse, childhood from the second to the sixth grades was classified into four groups: decreased, low maintenance, increased, and no maltreatment type. In addition, early adolescence from the fifth grade of elementary school to the third grade of middle school was also classified into the same types. Second, in emotional abuse, childhood was classified into three groups: decreased, increased, and no maltreatment type. Early adolescence was classified into four groups: decreased, low maintenance, increased, and no maltreatment type. Third, in neglect, childhood was classified into four groups: maintenance, low decreasing, low increasing, and no maltreatment type. Early adolescence was classified into three groups: maintenance, low increasing, and no maltreatment type. According to the change of child maltreatment by developmental period, physical abuse continued from childhood to early adolescence, whereas emotional abuse and neglect increased in early adolescence compared to childhood. This study is meaningful in classifying latent classes depending on maltreatment types. Theoretical and practical implications were suggested based on the study results.