• Title/Summary/Keyword: selection bias

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Postoperative Radiotherapy Improves Survival in Gastric Signet-Ring Cell Carcinoma: a SEER Database Analysis

  • Wei, Feng;Lyu, Hongwei;Wang, Shuoer;Chu, Yan;Chen, Fengyuan
    • Journal of Gastric Cancer
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    • v.19 no.4
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    • pp.393-407
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    • 2019
  • Purpose: To identify the potential therapeutic role of postoperative radiotherapy (RT) in patients with locally advanced (stage II and stage III) gastric signet ring cell carcinoma (SRC). Materials and methods: Patients with locally advanced gastric SRC from the Surveillance, Epidemiology, and End Results program database between 2004 and 2012 were included in our study. Univariate and multivariate Cox proportional models were performed, and survival curves were generated to evaluate the prognostic effect of postoperative RT and surgery alone on SRC patients. Propensity score matching (PSM) was used to avoid selection bias among the study cohorts. Results: We found that patients with postoperative RT had better probability of survival compared with those who did not receive RT (overall survival [OS], P<0.001; cancer-specific survival [CSS], P<0.001). After PSM, analysis of both overall and CSS showed that patients who underwent postoperative RT had better prognosis than those receiving surgery alone in the matched cohort (OS, P=0.00079; CSS, P=0.0036). Multivariate Cox proportional model indicated that postoperative RT had better effect on prognosis compared with surgery alone with respect to both overall (hazard ratio [HR], 0.716; 95% confidence interval [95% CI], 0.590-0.87; P=0.001) and CSS (HR, 0.713; 95% CI, 0.570-0.890; P=0.003). Conclusions: Postoperative RT had better prognosis compared with surgery alone for both overall and CSS for patients with locally advanced gastric SRC.

Feasibility of Linear-Shaped Gastroduodenostomy during the Performance of Totally Robotic Distal Gastrectomy

  • Wang, Bo;Son, Sang-Yong;Shin, Hojung;Roh, Chul Kyu;Hur, Hoon;Han, Sang-Uk
    • Journal of Gastric Cancer
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    • v.19 no.4
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    • pp.438-450
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    • 2019
  • Purpose: Although linear-shaped gastroduodenostomy (LSGD) was reported to be a feasible and reliable method of Billroth I anastomosis in patients undergoing totally laparoscopic distal gastrectomy (TLDG), the feasibility of LSGD for patients undergoing totally robotic distal gastrectomy (TRDG) has not been determined. This study compared the feasibility of LSGD in patients undergoing TRDG and TLDG. Materials and Methods: All c: onsecutive patients who underwent LSGD after distal gastrectomy for gastric cancer between January 2009 and December 2017 were analyzed retrospectively. Propensity score matching (PSM) analysis was performed to reduce the selection bias between TRDG and TLDG. Short-term outcomes, functional outcomes, learning curve, and risk factors for postoperative complications were analyzed. Results: This analysis included 414 patients, of whom 275 underwent laparoscopy and 139 underwent robotic surgery. PSM analysis showed that operation time was significantly longer (163.5 vs. 132.1 minutes, P<0.001) and postoperative hospital stay significantly shorter (6.2 vs. 7.5 days, P<0.003) in patients who underwent TRDG than in patients who underwent TLDG. Operation time was the independent risk factor for LSGD after intracorporeal gastroduodenostomy. Cumulative sum analysis showed no definitive turning point in the TRDG learning curve. Long-term endoscopic findings revealed similar results in the two groups, but bile reflux at 5 years showed significantly better improvement in the TLDG group than in the TRDG group (P=0.016). Conclusions: LSGD is feasible in TRDG, with short-term and long-term outcomes comparable to that in TLDG. LSGD may be a good option for intracorporeal Billroth I anastomosis in patients undergoing TRDG.

Effectiveness of Soyo-san (Xiaoyao-san) and its Modifications on Chronic Fatigue Syndrome: a Systematic Review and Meta-analysis (만성피로증후군에 대한 소요산(逍遙散)과 그 변방(變方)의 효과 : 메타분석을 통한 체계적인 문헌고찰)

  • Kim, Junyeol;Song, Jeongyun;Nam, Donghyun
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.34 no.3
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    • pp.117-125
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    • 2020
  • The purpose of this review is to confirm whether Soyo-san (Xiaoyao-san) and its modifications is effective on alleviating clinical symptoms in chronic fatigue syndrome (CFS) patients. We collected clinical trials (randomized controlled trial, quasi-randomized controlled trial, controlled clinical trial) to investigate the effects of Soyo-san and its modifications on general symptoms, fatigue, depression and anxiety in CFS patients. The databases used for data retrieval were Pubmed, Central Cochrane, Embase, CNKI, CQVIP, Wanfang, CiNii, OASIS, RISS, and Koreamed. We performed selection/exclusion process from the found studies to conform with prespecified criteria, and assessed the final included trials according to the Cochrane risk of bias tool. The included studies were classified based on the interventions in experimental and control group. Eight randomized controlled trials and one controlled clinical trial (total 921 participants) were eligible and their results were synthesized in the meta analysis. The synthesis showed a considerable effect of Soyo-san and its modifications on improvement of general symptoms (relative risk 0.27 [95% CI 0.19 to 0.39], Z=7.03, P<0.00001; I2=0%) and fatigue severity (SMD -1.20 [95% CI -1.46 to -0.93], Z=8.78, P<0.00001; I2=52%) in CFS patients, while Effect on depression and anxiety were inconclusive. We found that Soyo-san and its modifications were effective for improvement of general symptoms and fatigue severity in CFS post-treatment.

The Study for ENHPP Software Reliability Growth Model Based on Kappa(2) Coverage Function (Kappa(2) 커버리지 함수를 이용한 ENHPP 소프트웨어 신뢰성장모형에 관한 연구)

  • Kim, Hee-Cheul
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.12
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    • pp.2311-2318
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    • 2007
  • Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. Accurate predictions of software release times, and estimation of the reliability and availability of a software product require Release times of a critical element of the software testing process : test coverage. This model called Enhanced non-homogeneous Poission process(ENHPP). In this paper, exponential coverage and S-shaped model was reviewed, proposes the Kappa coverage model, which make out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE statistics and Kolmogorov distance, for the sake of efficient model, was employed. Numerical examples using real data set for the sake of proposing Kappa coverage model was employed. This analysis of failure data compared with the Kappaa coverage model and the existing model(using arithmetic and Laplace trend tests, bias tests) is presented.

The Study for NHPP Software Reliability Growth Model based on Burr Distribution (Burr 분포를 이용한 NHPP소프트웨어 신뢰성장모형에 관한 연구)

  • Kim, Hee-Cheul;Park, Jong-Goo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.3
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    • pp.514-522
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    • 2007
  • Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this parer, Goel-Okumoto and Yamada-Ohba-Osaki model was reviewed, proposes the Burr distribution reliability model, which making out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE, AIC statistics and Kolmogorov distance, for the sake of efficient model, was employed. Analysis of failure using real data set for the sake of proposing shape parameter of the Burr distribution was employed. This analysis of failure data compared with the Burr distribution model and the existing model(using arithmetic and Laplace trend tests, bias tests) is presented.

Validation and selection of GCPs obtained from ERS SAR and the SRTM DEM: Application to SPOT DEM Construction

  • Jung, Hyung-Sup;Hong, Sang-Hoon;Won, Joong-Sun
    • Korean Journal of Remote Sensing
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    • v.24 no.5
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    • pp.483-496
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    • 2008
  • Qualified ground control points (GCPs) are required to construct a digital elevation model (DEM) from a pushbroom stereo pair. An inverse geolocation algorithm for extracting GCPs from ERS SAR data and the SRTM DEM was recently developed. However, not all GCPs established by this method are accurate enough for direct application to the geometric correction of pushbroom images such as SPOT, IRS, etc, and thus a method for selecting and removing inaccurate points from the sets of GCPs is needed. In this study, we propose a method for evaluating GCP accuracy and winnowing sets of GCPs through orientation modeling of pushbroom image and validate performance of this method using SPOT stereo pair of Daejon City. It has been found that the statistical distribution of GCP positional errors is approximately Gaussian without bias, and that the residual errors estimated by orientation modeling have a linear relationship with the positional errors. Inaccurate GCPs have large positional errors and can be iteratively eliminated by thresholding the residual errors. Forty-one GCPs were initially extracted for the test, with mean the positional error values of 25.6m, 2.5m and -6.1m in the X-, Y- and Z-directions, respectively, and standard deviations of 62.4m, 37.6m and 15.0m. Twenty-one GCPs were eliminated by the proposed method, resulting in the standard deviations of the positional errors of the 20 final GCPs being reduced to 13.9m, 8.5m and 7.5m in the X-, Y- and Z-directions, respectively. Orientation modeling of the SPOT stereo pair was performed using the 20 GCPs, and the model was checked against 15 map-based points. The root mean square errors (RMSEs) of the model were 10.4m, 7.1m and 12.1m in X-, Y- and Z-directions, respectively. A SPOT DEM with a 20m ground resolution was successfully constructed using a automatic matching procedure.

The effect of public housing on depression (공공임대주택거주가 우울에 미치는 영향)

  • Lim, Se-hee
    • Korean Journal of Social Welfare Studies
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    • v.44 no.3
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    • pp.5-30
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    • 2013
  • The aim of this study is to identify the influence of public housing on depression of its residents by analyzing the 7th Korea welfare panel study. To reduce the selection bias which arise from the public housing is selected by personal choice, we used PSM(propensity score matching). In addition, we merged the result of PSM and OLS regression to control the other variables which can affect depression of the resident of public housing. Final result revealed that the statistical significance which was observed when we compared the level of depression between the residents of public housing and general community by independent t-test was not observed when we used the merged result from PSM and regression. These results suggest that the high level of depression in the residents of public housing might be related with their demographic characteristics or earned income not with the public housing itself. This study can be the evidence supporting the policy of providing public housing because living in public housing did not give negative influence on its residents. Considering that this study also showed that there were no observable positive influences of public housing, we can suggest that public housing policy for majority of people not limited to people with low income.

An analysis of the income impact of Self-Sufficiency training Program - by using Propensity Score Matching - (자활직업훈련 사업의 임금 효과 분석 - Propensity Score Matching 방법으로 -)

  • Yeon, Ahn-seo
    • Korean Journal of Social Welfare Studies
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    • no.37
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    • pp.171-197
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    • 2008
  • This study focuses on the following question; self-supporting training program increases participants' income compare to non-participants who have similar characteristics. This question is based on counterfactual assumption. In other words, this study concentrates on what the outcomes would have been if the participants were to be absent. This study adopts a quasi-experimental design. To overcome previous study's methodological weaknesses, especially selection bias, I applied matching procedure based on a propensity-score matching. Matching process was performed by using 'MatchIt' software. The major findings are as follows From Least Squares Regression analysis, I found the poor's income are significantly different according to age, pre-intervention earning, material status, and participation of training. Since the poor have homogeneous education level, education variable was not statistically significant. From the Simulation Quantities of Interest analysis, I also found that treatment group's expected incomes are lower than control's expected incomes. In other words, participation of training has a negative effect on the participants' earnings.

Assessing Hydrologic Impacts of Climate Change in the Mankyung Watershed with Different GCM Spatial Downscaling Methods (GCM 공간상세화 방법별 기후변화에 따른 수문영향 평가 - 만경강 유역을 중심으로 -)

  • Kim, Dong-Hyeon;Jang, Taeil;Hwang, Syewoon;Cho, Jaepil
    • Journal of The Korean Society of Agricultural Engineers
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    • v.61 no.6
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    • pp.81-92
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    • 2019
  • The objective of this study is to evaluate hydrologic impacts of climate change according to downscaling methods using the Soil and Water Assessment Tool (SWAT) model at watershed scale. We used the APCC Integrated Modeling Solution (AIMS) for assessing various General Circulation Models (GCMs) and downscaling methods. AIMS provides three downscaling methods: 1) BCSA (Bias-Correction & Stochastic Analogue), 2) Simple Quantile Mapping (SQM), 3) SDQDM (Spatial Disaggregation and Quantile Delta Mapping). To assess future hydrologic responses of climate change, we adopted three GCMs: CESM1-BGC for flood, MIROC-ESM for drought, and HadGEM2-AO for Korea Meteorological Administration (KMA) national standard scenario. Combined nine climate change scenarios were assessed by Expert Team on Climate Change Detection and Indices (ETCCDI). SWAT model was established at the Mankyung watershed and the applicability assessment was completed by performing calibration and validation from 2008 to 2017. Historical reproducibility results from BCSA, SQM, SDQDM of three GCMs show different patterns on annual precipitation, maximum temperature, and four selected ETCCDI. BCSA and SQM showed high historical reproducibility compared with the observed data, however SDQDM was underestimated, possibly due to the uncertainty of future climate data. Future hydrologic responses presented greater variability in SQM and relatively less variability in BCSA and SDQDM. This study implies that reasonable selection of GCMs and downscaling methods considering research objective is important and necessary to minimize uncertainty of climate change scenarios.

Efficacy of intralipid administration to improve in vitro fertilization outcomes: A systematic review and meta-analysis

  • Han, E Jung;Lee, Hye Nam;Kim, Min Kyoung;Lyu, Sang Woo;Lee, Woo Sik
    • Clinical and Experimental Reproductive Medicine
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    • v.48 no.3
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    • pp.203-210
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    • 2021
  • We performed a systematic review and meta-analysis to evaluate whether intralipid administration improved the outcomes of in vitro fertilization. Online databases (PubMed, Cochrane Library, Medline, and Embase) were searched until March 2020. Only randomized controlled trials (RCTs) that assessed the role of intralipid administration during in vitro fertilization were considered. We analyzed the rates of clinical pregnancy and live birth as primary outcomes. Secondary outcomes included the rates of chemical pregnancy, ongoing pregnancy, and missed abortion. We reviewed and assessed the eligibility of 180 studies. Five RCTs including 840 patients (3 RCTs: women with repeated implantation failure, 1 RCT: women with recurrent spontaneous abortion, 1 RCT: women who had experienced implantation failure more than once) met the selection criteria. When compared with the control group, intralipid administration significantly improved the clinical pregnancy rate (risk ratio [RR], 1.48; 95% confidence interval [CI], 1.23-1.79), ongoing pregnancy rate (RR, 1.82; 95% CI, 1.31-2.53), and live birth rate (RR, 1.85; 95% CI, 1.44-2.38). However, intralipid administration had no beneficial effect on the miscarriage rate (RR, 0.75; 95% CI, 0.48-1.17). A funnel plot analysis revealed no publication bias. Our findings suggest that intralipid administration may benefit women undergoing in vitro fertilization, especially those who have experienced repeated implantation failure or recurrent spontaneous abortion. However, larger, well-designed studies are needed to confirm these findings.