• 응용통계연구
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• 제34권4호
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• pp.589-597
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• 2021

단순회귀와 다중회귀에서 회귀계수의 의미는 차이가 있고 회귀계수의 추정값은 같지 않을 뿐 아니라 그 부호가 서로 다른 경우도 발생한다. 회귀모형에서 설명변수의 상대적 기여도의 파악은 회귀분석의 수행의 중요한 부분이다. 표준화 회귀모형에서 표준화 회귀계수는 해당 설명변수를 제외한 나머지 설명변수의 값이 고정되어있는 상황에서 설명변수가 표준편차만큼 증가하였을 때 반응변수가 표준편차를 기준으로 얼마나 변화했는가로 해석할 수 있지만 표준화 회귀계수의 크기가 각 설명변수의 상대적 중요도를 나타내는 척도라고 할 수 없음은 잘 알려져 있다. 본 논문에서는 다중회귀에서 회귀계수의 추정량을 상관계수와 결정계수의 함수로 나타내고 이를 추가적인 설명력과 추가적인 결정계수의 관점에서 생각해 본다. 또한 다양한 산점도에서의 상관계수와 회귀계수 추정값의 관계를 알아보고 설명변수가 두 개인 경우에 구체적으로 적용해 본다.

• Journal of the Korean Data and Information Science Society
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• 제26권2호
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• pp.505-516
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• 2015

We consider sparse high-dimensional linear regression models. Penalized regressions have been used as effective methods for variable selection and estimation in high-dimensional models. In penalized regressions, it is common practice to standardize variables before fitting a penalized model and then fit a penalized model with standardized variables. Finally, the estimated coefficients from a penalized model are recovered to the scale on original variables. However, these procedures produce a slightly different solution compared to the corresponding original penalized problem. In this paper, we investigate issues on the standardization of variables in penalized regressions and formulate the definition of the standardized penalized estimator. In addition, we compare the original penalized estimator with the standardized penalized estimator through simulation studies and real data analysis.

• Journal of Nutrition and Health
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• 제31권3호
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• pp.354-362
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• 1998

The purposes of this study were to develop standardized indices of staffing needs in each school, foodservice system through work sampling methodology . Conventional school foodservices were classified into 5 groups depending on size of meals served. Commissary school foodservices were also classified into 5 groups by cluster analysis using number of meals served, number of satellite schools, and time for transportation of food. Work measurement through work sampling methodology was conducted in 15 conventional and 21 commissary foodservices during 3 consecutive days from September to October in 1995. Statistical data analysis was completed using the SAS programs for descriptive analysis, cluster analysis, and simple linear regression. The results were as follows : Average points of leveling factors of conventional and commissary foodservices were 1.066 and 1.061 , respectively. Mean labor hours per work force was 328 minutes and 366 minutes in conventional and commissary foodservice , respectively. Standardized work time was calculated using leveling factor, ILO allowance rate (175) , and observational work time. The model for standardized indices of staffing needs was developed based on simple linear regression in each school foodservice system. In conventional school foodservice systems(for 100-1,900 meals per day) standardized staffing needs=3.2497 +0.005267$\times$number of meals served (F=273.1, R-square 0.9750, p<0.001). In commissary school foodservice systems (for 200-1,600 meals per day ) Standardized staffing needs=3.393384 +0.0063$\times$number of meals served (F=30.78, R-square 0.6580, p<0.001).

• Journal of the Korean Data and Information Science Society
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• 제21권3호
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• pp.447-459
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• 2010

본 연구는 메타분석에서 헤지의 표준화된 평균차를 이용하여 당뇨에 걸린 쥐들에게 프로폴리스를 투여하여 체중, 혈당량, 콜레스테롤, 트리글리세리드의 평균비교를 통해 프로폴리스의 항-당뇨 효과에 대해 알아보았다. 고정효과모형을 적용시킨 결과 혈당량의 감소, 콜레스테롤 농도의 감소, 트리글리세리드 농도의 감소에 대해 유의한 효과를 보였고, 동질성 검정을 통해 동질성을 만족하지 않은 모든 변수에 대해 랜덤효과모형을 적용시킨 결과 혈당량의 감소와 트리글리세리드 농도의 감소에 대해 유의한 효과를 나타냈다. 또한 프로폴리스의 투여기간과 투여량에 대해 메타회귀분석을 실시한 결과, 투여기간이 체중, 혈당량, 콜레스테롤에 유의한 변수로 나타났다.

• Journal of the Korean Data and Information Science Society
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• 제22권4호
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• pp.717-726
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• 2011

본 연구는 메타분석을 이용하여 녹차를 투여한 당뇨 유발 쥐들의 체중과 혈액 내 혈당량, 총 콜레스테롤, 중성지방, 고농도지단백 콜레스테롤의 평균비교를 통해 녹차의 항-당뇨 효과에 대해 알아보고자 한다. 헤지의 표준화된 평균차에서 고정효과모형을 적용한 결과 체중은 통계적으로 유의한 증가를 보였으며, 혈액 내 혈당량과 중성지방은 통계적으로 유의한 감소를 보였다. 동질성 검정을 통해 이질성을 보인 모든 변수에 대해 랜덤효과모형을 적용시킨 결과 체중은 유의한 증가를 보였으며, 혈액 내 혈당량은 유의한 감소를 보였다. 또한 녹차의 투여기간이 변수에 영향을 미치는지 알아보기 위해 메타회귀분석을 실시한 결과 모든 변수에 대해 녹차의 투여기간이 유의하지 않았다.

• 한국의류산업학회지
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• 제17권2호
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• pp.278-286
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• 2015

Fashion industry has tried to adopt the virtual garment technology to reduce the time and effort spent on sample creation. For garment manufacturers to adopt the virtual garment technology as an alternative to sample creation, 3D avatars that meet the needs of each brand should be developed. Virtual garment softwares that are available in the market provide avatars with standardized body models and allow to modify the size by manually entering size specifications. This study proposed a methodology to develop size specifications for 3D avatars as well as brand-customized production sizes. For this, a man's fashion brand which is using virtual garment technology is selected. And the Size Korea database is used to develop size specification based on the customers' body shape. This study developed regression equations on body size specifications, which in turn proposed a regression model to proportionately change size specifications of 3D fitting-models. Based on the each body size calculated by the regression model, a standard model is created, and the skeleton-skin algorithm is applied to the regression model to obtain the results of size changes. Then, the 3D model sizes are tested for size changes as well as measured, which verifies that the regression model reflects body size changes.

• Environmental Engineering Research
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• 제19권1호
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• pp.31-36
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• 2014

In this study, the influence of the control and operational parameters within a sewage treatment plant were reviewed by performing multiple regression analysis on the effluent quality of the sewage treatment. The data used for this review are based on the actual data from a sewage treatment plant using the media process within the year 2012. The prediction models of chemical oxygen demand ($COD_{Mn}$) and total nitrogen (T-N) within the effluent of the 2nd settling tank based on the multiple regression analysis yielded the prediction accuracy measurements of 0.93 and 0.84, respectively; and it was concluded that the model was accurately predicting the variances of the actual observed values. If the data on the energy spent on each operating condition can be collected, then the operating parameter that conserves energy without violating the effluent quality standards of COD and T-N can be determined using the regression model and the standardized regression coefficients. These results can provide appropriate operation guidelines to conserve energy to the operators at sewage treatment plants that consume a lot of energy.

• 보건행정학회지
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• 제25권3호
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• pp.197-206
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• 2015

Background: The purpose of this study was to propose a method for developing a measure of hospital-wide all-cause risk-standardized readmissions using administrative claims data in Korea and to discuss further considerations in the refinement and implementation of the readmission measure. Methods: By adapting the methodology of the United States Center for Medicare & Medicaid Services for creating a 30-day readmission measure, we developed a 6-step approach for generating a comparable measure using Korean datasets. Using the 2010 Korean National Health Insurance (NHI) claims data as the development dataset, hierarchical regression models were fitted to calculate a hospital-wide all-cause risk-standardized readmission measure. Six regression models were fitted to calculate the readmission rates of six clinical condition groups, respectively and a single, weighted, overall readmission rate was calculated from the readmission rates of these subgroups. Lastly, the case mix differences among hospitals were risk-adjusted using patient-level comorbidity variables. The model was validated using the 2009 NHI claims data as the validation dataset. Results: The unadjusted, hospital-wide all-cause readmission rate was 13.37%, and the adjusted risk-standardized rate was 10.90%, varying by hospital type. The highest risk-standardized readmission rate was in hospitals (11.43%), followed by general hospitals (9.40%) and tertiary hospitals (7.04%). Conclusion: The newly developed, hospital-wide all-cause readmission measure can be used in quality and performance evaluations of hospitals in Korea. Needed are further methodological refinements of the readmission measures and also strategies to implement the measure as a hospital performance indicator.

• Animal Bioscience
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• 제37권6호
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• pp.1077-1084
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• 2024

Objective: The present work was conducted to evaluate suitable variables and develop prediction equations using chemical composition and physical characteristics for estimating standardized ileal digestibility (SID) of lysine (Lys) in full-fat soybeans (FFSB). Methods: The chemical composition and physical characteristics were determined including trypsin inhibitor activity (TIA), urease activity (UA), protein solubility in 0.2% potassium hydroxide (KOH), protein dispersibility index (PDI), lysine to crude protein ratio (Lys:CP), reactive Lys:CP ratio, neutral detergent fiber, neutral detergent insoluble nitrogen (NDIN), acid detergent insoluble nitrogen (ADIN), acid detergent fiber, L* (lightness), and a* (redness). Pearson's correlation (r) was computed, and the relationship between variables was determined by linear or quadratic regression. Stepwise multiple regression was performed to develop prediction equations for SID of Lys. Results: Negative correlations (p<0.01) between SID of Lys and protein quality indicators were observed for TIA (r = -0.80), PDI (r = -0.80), and UA (r = -0.76). The SID of Lys also showed a quadratic response (p<0.01) to UA, NDIN, TIA, L*, KOH, a* and Lys:CP. The best-fit model for predicting SID of Lys in FFSB included TIA, UA, NDIN, and ADIN, resulting in the highest coefficient of determination (R² = 0.94). Conclusion: Quadratic regression with one variable indicated the high accuracy for UA, NDIN, TIA, and PDI. The multiple linear regression including TIA, UA, NDIN, and ADIN is an alternative model used to predict SID of Lys in FFSB to improve the accuracy. Therefore, multiple indicators are warranted to assess either insufficient or excessive heat treatment accurately, which can be employed by the feed industry as measures for quality control purposes to predict SID of Lys in FFSB.

• Journal of Nutrition and Health
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• 제39권4호
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• pp.417-425
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• 2006

The purpose of this study were to a) investigate operation of human resource in contract foodservice management company (CFMC), b) identify the staffing indices for the establishment an labor productivity for CFMC, and c) develop standardized model of staffing demand as foodservice's scale in CFMC. The data was collected using FS intra-net system from 138 contract-managed foodservice operations in A CFMC and statistical analysis was completed using the SAS/win package (ver. 8.0) for description analysis, ANOVA, Duncan multiple comparison, pearson correlation analysis, and regression analysis. The types of operation were included factory (45%), small scale operation (26%), office (11%), department store (10%), training institute (4%), and hospital (3%). The distribution of foodservice scale was classified by meal served was as follows; 'less than 500 meals (47%)', 'from 500 to 1500 meals (25%)', 'from 1500 to 2500 meals (17%)', and 'more than 2500 meals (12%)'. There was two types of contract method, fee-contract (53%) and profit-and-loss contract (46%) Some variables were significantly high operation indices such as selling price, food cost, monthly sales, net profit and others were significantly low operation indices such as labor, meal time a day in the small foodservice on meal scale (p<.001). The more foodservice was large, the more human resource was disposed on dietitian, cook, cooking employee altogether (p<.001). Foodservice in A CFMC was divided into 2 groups by 500 meals a day, according to comparative analysis of labor productivity as meal scale per working hour, meal scale a day and operation indices as meal per foodservice employee, meal per cooking employee (p<.001). The regression equation model was developed as 'the number of employees=1.82+0.014 ${\times}$ meal served' in the operation of less than 500 meals, 'the number of employees=9.42+0.013 ${\times}$ meal scale a day -0.94 ${\times}$ meal scale per working hour' in the operation over 500 meal scale using labor productivity indices and operation indices. Therefore, CFMC could be enhanced efficiency of human resource arrangement using the standardized model of staffing demand and would be increased effectiveness of profit.