• Title/Summary/Keyword: Stepwise regression

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Variable selection in partial linear regression using the least angle regression (부분선형모형에서 LARS를 이용한 변수선택)

  • Seo, Han Son;Yoon, Min;Lee, Hakbae
    • The Korean Journal of Applied Statistics
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    • v.34 no.6
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    • pp.937-944
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    • 2021
  • The problem of selecting variables is addressed in partial linear regression. Model selection for partial linear models is not easy since it involves nonparametric estimation such as smoothing parameter selection and estimation for linear explanatory variables. In this work, several approaches for variable selection are proposed using a fast forward selection algorithm, least angle regression (LARS). The proposed procedures use t-test, all possible regressions comparisons or stepwise selection process with variables selected by LARS. An example based on real data and a simulation study on the performance of the suggested procedures are presented.

Evaluation of Beef Freshness Using Visible-near Infrared Reflectance Spectra (가시광선-근적외선 반사스펙트럼을 이용한 쇠고기의 신선도 평가)

  • Choi, Chang-Hyun;Kim, Jong-Hun;Kim, Yong-Joo
    • Food Science of Animal Resources
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    • v.31 no.1
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    • pp.115-121
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    • 2011
  • The objective of this study was to develop models to predict freshness factors (total viable counts (TVC), pH, volatile basic nitrogen (VBN), trimethylamine (TMA), and thiobarbituric acid (TBA) values) and the storage period in beef using a visible and near-infrared (NIR) spectroscopic technique. A total of 216 beef spectra were collected during the storage period from 0 to 14 d at a $10^{\circ}C$ storage. A spectrophotometer was used to measure reflectance spectra from beef samples, and beef freshness spectra were divided into a calibration set and a validation set. Multi-linear regression (MLR) models using the stepwise method were developed to predict the factors. The MLR results showed that beef freshness had a good correlation between the predicted and measured factors using the selected wavelength. The correlation of determination ($r^2$), standard error of prediction (SEP), and ratio of standard deviation to SEP (RPD) of the prediction set for TVC was 0.74, 0.64, and 2.75 Log CFU/$cm^2$, respectively. The $r^2$, SEP, and RPD values for pH were 0.43, 0.10, and 1.10; those for VBN were 0.73, 1.45, and 2.00 mg%; those for TMA were 0.70, 0.19, and 2.58 mg%; those for TBA values were 0.73, 0.13, and 2.77 mg MA/kg; and those for storage period were 0.77, 1.94, and 2.53 d, respectively. The results indicate that visible and NIR spectroscopy can predict beef freshness during storage.

Predictors of Weight Control Behavior According to College Students' BMI, Perception of Body Shape, Obesity Stress, and Self-Esteem (대학생의 체질량지수, 체형인식, 비만스트레스, 자아존중감에 따른 체중조절행동 예측요인)

  • Kim, Jong-Im
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.6
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    • pp.438-448
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    • 2016
  • This study was conducted to identify factors influencing the weight control behavior of college students. The subjects included college students in the C area, and data were collected through a self reported structured questionnaire from Dec 01 to 20 of 2015. Overall, 289 subjects were analyzed. Analyses consisted of descriptive statistics, t-tests, ANOVA, Pearson's correlation analysis, and stepwise multiple regression analysis. The findings showed a prominent distortion of college students' perceptions of their bodies based on evaluation by others and obesity stress, which had special impacts on their weight control behavior. Weight control behavior, body self-awareness (r=.31, p<0.001), assessment of body by others (r=.30, p<0.001), and obesity stress (r=.43, p<0.001) were closely related to their weight control behavior. Stepwise multiple regression revealed that their weight control behavior was closely influenced by obesity stress (${\beta}=.37$, p<0.001) and assessment of body by others (${\beta}=.15$, p=0.009). These variables accounted for 20% of the weight control behavior (F=37.30, p<0.001). Overall, assessment of body by others and obesity stress were found to be predictors of their weight control behavior. These findings indicate that it is necessary to develop and implement information programs and design appropriate prevention programs that can induce healthy weight control behaviors. Such programs should include health education, as well as intervention programs to identify such predictors and help college students judge and perceive their body shapes objectively so that they control their weight in a proper manner.

Estimated Headwater Stream Temperature Using Environmental Factors with Seasonal Variations in a Forested Catchment (환경인자를 이용한 산지계류의 계절별 수온변화 예측)

  • Nam, Sooyoun;Jang, Su-Jin;Kim, Suk-Woo;Lee, Youn-Tae;Chun, Kun-Woo
    • Korean Journal of Environment and Ecology
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    • v.34 no.1
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    • pp.55-62
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    • 2020
  • To estimate headwater stream temperature with seasonal variations, we analyzed precipitation, runoff and air temperature in experimental forest of Kangwon National University, Gangwon-do (2017~2018 years). The daily mean value of headwater stream temperature for spring was 6.9~17.7℃ and correlated with air temperature, that for summer and fall were 12.2~26.3℃ and 3.6~19.3℃, correlated with air temperature and runoff. Based on seasonal variations, we applied for stepwise multiple linear regression analyses to estimate headwater stream temperature with seasonal variations. The equations were headwater stream temperature(WT)spring=(0.553×Air temperature)+(0.086×Runoff)+4.145 (R2=0.505; p<0.01), WTsummer=(0.756×Air temperature)+(-0.072×Runoff)+2.670 (R2=0.510; p<0.01), and WTfall=(0.738×Air temperature)+(0.028×Precipitation)+2.660 (R2=0.844; p<0.01). The coefficient of determination (R2) was greater than when it was estimated by air temperature in all seasons and progressively increased from spring to winter. Therefore, we indicated difference on estimated magnitude of stepwise multiple linear regression, due to effects on headwater stream temperature of different environmental factors with seasonal variations. Furthermore, temporal factors with spatial characteristics (e.g., river versus headwater stream) could be recommended for estimating headwater stream temperature.

Analysis of the Clinical Nurses' Organizational Commitment and Relating Variables. (임상간호사의 조직몰입과 관련변인 분석)

  • Kim, Jung-Hee
    • Journal of Korean Academy of Nursing Administration
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    • v.2 no.1
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    • pp.125-139
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    • 1996
  • Organizational commitment is characterized by a strong belief in and acceptance of the organization's goal and values ; a willingness to exert considerable effort on behalf of the organization ; a strong desire to maintain membership in the organization. The purpose of this study was to identify the variables which influence the organizational commitment and to test the relationship between the clinical nurses' organizational commitment and turnover intention. The subjects were 412 nurses who were working on general wards at three General Hospitals in Chounbuk. The data were collected by self-reporting questionnaire from Sept. 20 to Sept. 31, 1995. The instruments used in this study were Likert-type scale which were Organizational Commitment Scale by Mowday et al, and Turnover Intention Scale by Mobley et al. The questionnaire of organizational characteristics was made through reviewing literature. The data were analyzed by frequency, percentage, t-test, one-way ANOVA, Scheffe test, Pearson's correlation coefficient, and stepwise multiple regression with $SPSS-PC^+$ program. Major findings are as follows : 1. Mean scores for organizational commitment were 3.008 and turnover intention 3.167 on a 5 point scale. 2. Age and clinical experience were positively related to organizational commitment(r=.4806, p=.000; r=.4792, p=.000). 3. In the personal variables, hospital type(F=21.374, p=.000), education level(F=5.481, p=.001), position(F=30.867, P=.000), and marital status(t=-5.63, p=.000) of the nurses showed significant differences in organizational commitment. 4. The variables to the organizational characteristic were statistically significant in organizational commitment : formalization(r=.3458, p=.000), human-centered organizational characteristic(r=.4302, p=.000), performance- centered organizational characteristic(r=-.1502, p=.000), payment(r=.2234, p=.000), promotion(r=.2710, p=.000), benefit & service(r=.2325, p=.000), and resource inadequacy(r=-.2172, p=.000). 5. For the purpose of identifying the predicting variables in organizational commitment, stepwise multiple regression is conducted. The results show that age, human-centered organizational characteristic, formalization, hospital type, resource inadequacy, promotion, and benefit & service were significant variables and explained 46% of the variance. 6. Organizational commitment was significantly negatively correlated with turnover intention(r=-.6442, p=.000). As a result of stepwise multiple regression analysis, organizational commitment is the most powerful variable predicting turnover intention and explained 41.5% of the variance. In conclusion, this study shows that the higher the organizational commitment level, the lower the turnover intention. Therefore, for effective turnover management, it is important to improve the organizational commitment among clinical nurses. In order to enhance the organizational commitment by the clinical nurses, it will be useful to consider significant organizational characteristics variables identified in this study.

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A Study on the Evaluation of the Residential Environment of the Permanent Rental Housing in Busan Using Stepwise Logistic Regression (Stepwise Logistic Regression을 이용한 부산지역 영구임대주택의 주거환경 수준 평가 분석)

  • Choi, Yeol;Kim, Hyeong Jun;Chun, Sun Mi
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.5
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    • pp.2147-2156
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    • 2013
  • This study aims to analyze the evaluation of the residential environment on the permanent rental housing in Busan. The Permanent Rental Housing policy is one of the special measures which contribute to getting the low-income urban dwellers settled in places of their own. Unfortunately the government has focused on expanding the quantity of housing even though housing doesn't mean just a physical object but the foundation of life. So the occupants who answered the survey lived in the permanent rental housing which were constructed by Busan Metropolitan Corporation. The purpose of the study is to give suggestions which can make up for dissatisfaction and apply preference of occupants based on the results of the research. The result of this study is in following; there were few significant managerial variables determinants of residential satisfaction. And significant variables are; position of rooms and bathroom facilities in internal building characteristics, color of apartment and playground in exterior building characteristics, commuting distance and viewshaft in locational characteristics. Therefore, the government needs to use cutting edge housing technologies aimed at improvement of residential environment and achievement of affordable expense simultaneously.

Safety-practice and Its Related Factors among Elementary students in a rural area (일부 초등학생의 안전실천 관련요인)

  • Lee, Young-Mee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.5
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    • pp.1115-1125
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    • 2009
  • Purpose: The purpose of this study was to investigate the Safety-practice and Its Related Factors among Elementary students in rural area, to provide the basic data for prevention for safety accident occurrence in order to improve the QOL. Methods: The subjects of this study were 549 elementary students using self-report questionnaires. The collected data was analyzed using descriptive statistics, t-test, ANOVA, Scheffe's test, Pearson correlation coefficient and stepwise multiple regression with SPSS 12.0 Program. Results: The mean score for level of the safety awareness was 3.55(${\pm}.36$) and of the safety practice, 2.98(${\pm}.48$). The score of Safety-practice was statistically significant difference according to students' gender(p= .028) and students' grade(p= .004), the number of friends(p= .002), the level of school life adaptation(p= .000), recognized learning proficiency(p= .000), personality(p= .005), curiosity(p= .003), the level of demand for safety education(p= .000), the level of safety-education conducted by parents(p= .000), the level of safety-education conducted by teacher(p= .000). Stepwise multiple regression analysis for Safety-practice revealed that the most powerful predictor was level of Safety-awareness and self-esteem, the level of safety-education conducted by parents explained 28.8% of the variance. Conclusions: Therefore, it is necessary to develop safety practice promotion program in order to enhance the quality of life of elementary students. Future studies need to be pursued to find various variances.

Factors Influencing Swallowing-related Quality of Life in Patients with Dysphagia (연하장애 환자의 삶의 질 영향 요인)

  • Kim, Ju-Yeun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.11
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    • pp.421-431
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    • 2016
  • The purpose of this study was to identify the influence of depression, social isolation, and meaning in life on the swallowing related quality of life in patients with dysphagia. In this study, 87 the dysphagia patients diagnosed with stroke, degenerative disease, and neurological disorder in a general or rehabilitation hospital in Seoul, Gyeonggi, and Incheon were assessed. The data were collected between February and April, 2015 using CES-D, RULS, PIL, SWAL-QOL. The data were analyzed using descriptive statistics, t-test, ANOVA, Pearson's correlation, and stepwise multiple regression with SPSS 22.0. Of the participants, 20.7% reported having had depression, 92.0% middle-high social isolation and 64.4% existential vacuum. The mean scores were SWAL- QOL 158.89(35.97). Stepwise multiple regression revealed that tube feeding to have the greatest effect on SWAL-QOL(${\beta}=-0.57$, p<.001), followed in order by age (${\beta}=0.26$, p=.001), lower MIL (${\beta}=0.19$ p=.014), and education (${\beta}=0.17$, p=.032). The most influential factor to SWAL-QOL was tube feeding. These variables accounted for 50.7% of SWAL-QOL in dysphagia patients (F=28.84 p=.031). Therefore, it is essential to develop the intervention that can improve the meaning in life in patients with dysphagia. In addition there is a need to study the psychological factors and quality of life of tube feeding.

Consideration on Precedence of Crime Occurrence on Stock Price of Security Company (범죄 발생의 경비업체 주가에 대한 선행성 고찰)

  • Joo, Il-Yeob
    • Korean Security Journal
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    • no.34
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    • pp.313-336
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    • 2013
  • The purpose of this study is to derive an optimal regression model for occurrences of major crimes on a security company's stock price through identifying precedence of the occurrences of major crimes on the security company's stock price, relationship between the occurrences of major crimes and the security company's stock price. Followings are the results of this study. First, the occurrences of murder crime, robbery crime, rape crime, theft crime move along the security company's monthly stock price simultaneously, and the occurrence of violence crime precedes 6 months to the security company's monthly stock price depending on the results of cross-correlation analysis of precedence of occurrences of major crimes, such as murder crime, robbery crime, rape crime, theft crime, violence crime on the security company's monthly stock price. Second, the explanation of the occurrences of robbery crime, rape crime, theft crime on the security company's monthly stock price is 61.7%($R^2$ = .617) excluding murder crime, violence crime depending on the results of multiple regression analysis(stepwise method) by putting the occurrences of major crimes, such as murder crime, robbery crime, rape crime, theft crime, violence crime into the security company's monthly stock price.

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A Study of Factors Influencing Health Promoting Behavior and Quality of Life in the Elderly (노인의 건강증진 행위 및 삶의 질에 영향을 미치는 요인)

  • 박은숙;김순자;김소인;전영자;이평숙;김행자;한금선
    • Journal of Korean Academy of Nursing
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    • v.28 no.3
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    • pp.638-649
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    • 1998
  • The purpose of this study was to investigate the factors influencing health promoting behavior and quality of life in the elderly, to provide the basic data for health promoting intervention in order to improve quality of life. The subjects of this study were 571 elderly person over the age of 65, living in Seoul, Korea, during the period from November, 1997 to January, 1998. The instruments for this study were the health promoting behavior scale developed by Walker et (1987), the quality of life scale by 노유자(1988), the health concept scale by Laffrey(1986), the perceived health states scale by Lawston et al. (1982), the health value scale by Wallston et al. (1978), the self esteem scale by Rogenberg(1965) and the self efficacy scale by Sherer(1982). The instruments for this study were pretested on the elderly for reliability and validity. The data were analyzed using descriptive statistics, t-test, Pearson correlation coefficients ANOVA and stepwise multiple regression. The results of this study are as follows ; 1. The health promoting behavior showed significant positive correlation with health concept, perception of health status, self esteem, internal health locus of control, self efficacy and quality of life in the elderly. 2. The quality of life showed significant positive correlation with health concept, perception of health status, self esteem, internal health locus of control, self efficacy in the elderly, 3. Stepwise multiple regression analysis revealed that the most powerful predictor of health promoting behavior was quality of life. A combination of quality of life, health concept, perceived health status, self esteem, internal health locus of control, and self efficacy accounted for 46% of the variance in health promoting behavior in the elderly. 4. Stepwise multiple regression analysis revealed that the most powerful predictor of quality of life in the elderly was self esteem. A combination of self esteem. A combination of self esteem, health concept, perceived health status. health promoting behavior and self efficacy accounted for 56% of the variance in quality of life in the elderly. From the results of the study, the following recommendations are presented as follow : 1. Development of a health promoting program to improve quality of life in the elderly. 2. In developing the health promoting program, the above major influencing factors be considered. 3. It is suggested that an education specialist in practice in the community be included in the program development.

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