• Title, Summary, Keyword: confounding factor

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Implementation and Features for Design of Experiment (품질실험계획 모형의 특징 및 적용방안)

  • Choi, Sung-Woon
    • Proceedings of the Safety Management and Science Conference
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    • pp.519-524
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    • 2010
  • The research presents implementation strategy and features for experimental design of quality. The MINITAB models of experimental design classfies by the kinds of factors, orthogonality, blocking, confounding and rotationability. The results discussed in this paper can be easily used for practictioners.

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The Study of the Influence of Induced Abortion on Secondary Infertility analyzed by Logistic Regression (Logistic Analysis를 이용하여 분석한 인공유산이 속발성불임에 미치는 영향)

  • Lee, Won-Chul
    • Journal of Preventive Medicine and Public Health
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    • v.15 no.1
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    • pp.179-186
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    • 1982
  • The methods controlling the confounding factors were discussed using the data of secondary infertility with induced abortion. Mantel-Haenszel method and logistic model were applied in the analysis to find out which factors were confounding and/or effect modification variables. In the logistic analysis, the main effect of induced abortion, spontaneous abortion, age and interaction effect between induced abortion and spontaneous abortion were chosen as independent variables being regressed into logistic functions. Spontaneons abortion was interpreted as a potential confounder and at the same time potential effect modifier and age was interpreted as potential confounder. Spontaneous abortion was shown to be more important influencing factor than age to the secondary infertility. In the course of logistic analysis, the problem of parameter estimation and hypothesis testing, assessing the fitness of a model, and selection of the best model were briefly explained. For the program of logistic model, FUNCAT Procedure of SAS package was chosen.

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Relationship between asthma and dental caries in Korean adults: Data from the Sixth Korea National Health and Nutrition Examination Survey (한국 성인의 천식과 치아우식과의 관련성:제 6기 국민건강영양조사 자료 이용)

  • Choi, Yoon-Young
    • Journal of Korean society of Dental Hygiene
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    • v.19 no.1
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    • pp.131-140
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    • 2019
  • Objectives: The purpose of this study was to evaluate the association between asthma and dental caries by using data from the Korean National Health and Nutrition Examination Survey (KNHANES), from 2013 to 2015. Methods: The study included 11,731 subjects who were ${\geq}19$ years of age and analyzed their demographic-, socioeconomic-, health-, and oral health care-related data. The chi-squared test and logistic regression analysis were conducted using complex sample analyses to examine the relationship between asthma and dental caries. Results: Compared with the control group, the risk for dental caries in the asthma group was 1.207 times higher, regardless of various confounding factors (p<0.001). In the asthma group, the mean DMFT score was significantly higher than that in the control group (p<0.001). After adjusting for confounding factors, the mean number of DMFT in subjects with asthma was 7.67, which was higher than that in subjects without asthma (7.28) (p<0.001). Conclusions: The study results show that asthma may be a risk factor for dental caries. Therefore, in order to prevent dental caries in asthma patients, oral hygiene education is important.

Estimation and Sensitivity Analysis on the Effect of Job Training for Non-Regular Employees (비정규직 직업훈련효과 추정과 민감도 분석)

  • Lee, Sang-Jun
    • The Korean Journal of Applied Statistics
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    • v.25 no.1
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    • pp.163-181
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    • 2012
  • This paper studies the effect of job training for non-regular employees in the Korea labor market. Using an economically active population data set of statistics Korea, we apply a non-parametric matching and sensitivity analysis method to measure the effect of the training for non-regular employees and to look for the impact of an unobservable variable or confounding factor in regards to the selection effect and outcome effect. In the our empirical results, we conclude that the effect of the training for non-regular employees has a better employment effect for getting a regular job rather than a wage effect; in addition, the impact of unobservable variables or confounding factors do not exercise a statistically strong influence on the baseline ATT.

Blocking Method of 2n Factorial and Fractional Factorial Designs in Blocks of Size Two by Using Defining Contrast (한 블록 당 실험의 크기가 2인 경우 정의대비를 이용한 2n요인실험과 그 일부실시법의 설계방법)

  • Choi, Byoung-Chul
    • Communications for Statistical Applications and Methods
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    • v.15 no.4
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    • pp.497-507
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    • 2008
  • Confounding techniques have to be used repeatedly in the situations where it is necessary to perform only 2 runs under homogeneous conditions in $2^m$ factorial and fractional factorial experiment. Combinations of confounded $2^m$ factorial and fractional factorial designs enable the estimation of all main effects and all of or a part of 2 factor interaction effects. Defining contrast are used for our designs and treatment combinations of designs to be run are presented.

Balanced Experimental Designs for cDNA Microarray data

  • Choi, Kuey-Chung
    • 한국데이터정보과학회:학술대회논문집
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    • pp.121-129
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    • 2006
  • Two color or cDNA microarrays are extensively used to study relative expression levels of thousands of genes simultaneously. 0かy two tissue samples can be hybridized on a single microarray slide. Thus, a microarray slide necessarily forms an incomplete block design with block size two when more than two tissue samples are under study. We also need to control for variability in gene expression values due to the two dyes. Thus, red and green dyes form the second blocking factor in addition to slides. General design problem for these microarray experiments is discussed in this paper. Designs for factorial cDNA microarrays are also discussed.

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A Study on the Sequential Analysis of Resolution IV $3^t$ Fractional Factorial Designs (Resolution IV $3^t$ 요인부분실험법의 축차 분석방법에 관한 연구)

  • Kim, Sang-Ik
    • Proceedings of the Korean Society for Quality Management Conference
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    • pp.129-138
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    • 2010
  • For the fractional factorial designs, the resolution-IV designs can be used when we want to estimate the main effects and to investigate the structure of the non-negligible two-factor interaction effects, when the three-factor and higher order interaction effects are all negligible. However we need to add the additional treatment combination in order to identify the influential interactions for the resolution-IV fracrtional factorial designs. In this paper we investigate the statistical structure for 3-level resolution-IV designs constructed by fold-over scheme and introduce a method for analyzing the influential two-factor interactions.

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A Study on the Statistical Structure and Additional Analysis of the 3-level Foldover Resolution IV Fractional Factorial Designs (3-수준계 Foldover Resolution IV 부분실험법의 통계적 구조 및 추가분석방법에 관한 연구)

  • Kim, Sang-Ik
    • Journal of the Korean Society for Quality Management
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    • v.38 no.1
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    • pp.42-51
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    • 2010
  • For the fractional factorial designs, the resolution-IV designs can be used when we want to estimate the main effects and to investigate the structure of the non-negligible two-factor interaction effects, when the three-factor and higher order interaction effects are all negligible. However we need to add the additional treatment combinations in order to identify the influential interactions for the resolution-IV fractional factorial designs. In this paper we investigate the statistical structure for 3-level resolution-IV designs constructed by fold-over scheme and introduce a method for analyzing the influential two-factor interactions.

A Study on the Methods for Assessing Construct Validity (구성 타당성 평가방법에 관한 연구)

  • 이광희;이선규;장성호
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.22 no.50
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    • pp.1-9
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    • 1999
  • The purpose of this study is to establish a basis for assessing construct validity of measures used in organizational research. The classic Campbell and Fiske's(1959) criteria are found to be lacking in their assumptions, diagnostic information, and power. The inherent confounding of measurement error with systematic trait and method effects is a severe limitation for a proper interpretation of convergent and discriminant validity. The confirmatory factor analysis(CFA) approach overcomes most of the limitations found in Campbell and Fiske's(1959) method. However, the CFA approach confounds random error with unique variance specific to a measure. The second-order confirmatory factor analysis(SOCFA) was shown to harbor rather restrictive assumptions and is unlikely to be met in practice. The first-order, multiple-informant, multiple-item(FOMIMI) model is a viable option, but it may also be of limited use because of the large number measures.

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Conditioning-induced cardioprotection: Aging as a confounding factor

  • Randhawa, Puneet Kaur;Bali, Anjana;Virdi, Jasleen Kaur;Jaggi, Amteshwar Singh
    • The Korean Journal of Physiology and Pharmacology
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    • v.22 no.5
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    • pp.467-479
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    • 2018
  • The aging process induces a plethora of changes in the body including alterations in hormonal regulation and metabolism in various organs including the heart. Aging is associated with marked increase in the vulnerability of the heart to ischemia-reperfusion injury. Furthermore, it significantly hampers the development of adaptive response to various forms of conditioning stimuli (pre/post/remote conditioning). Aging significantly impairs the activation of signaling pathways that mediate preconditioning-induced cardioprotection. It possibly impairs the uptake and release of adenosine, decreases the number of adenosine transporter sites and down-regulates the transcription of adenosine receptors in the myocardium to attenuate adenosine-mediated cardioprotection. Furthermore, aging decreases the expression of peroxisome proliferator-activated receptor gamma co-activator 1-alpha ($PGC-1{\alpha}$) and subsequent transcription of catalase enzyme which subsequently increases the oxidative stress and decreases the responsiveness to preconditioning stimuli in the senescent diabetic hearts. In addition, in the aged rat hearts, the conditioning stimulus fails to phosphorylate Akt kinase that is required for mediating cardioprotective signaling in the heart. Moreover, aging increases the concentration of $Na^+$ and $K^+$, connexin expression and caveolin abundance in the myocardium and increases the susceptibility to ischemia-reperfusion injury. In addition, aging also reduces the responsiveness to conditioning stimuli possibly due to reduced kinase signaling and reduced STAT-3 phosphorylation. However, aging is associated with an increase in MKP-1 phosphorylation, which dephosphorylates (deactivates) mitogen activated protein kinase that is involved in cardioprotective signaling. The present review describes aging as one of the major confounding factors in attenuating remote ischemic preconditioning-induced cardioprotection along with the possible mechanisms.