• Title/Summary/Keyword: Data Bias

Search Result 1,757, Processing Time 0.025 seconds

Ginseng consumption and risk of cancer: A meta-analysis

  • Jin, Xin;Che, Dao-biao;Zhang, Zhen-hai;Yan, Hong-mei;Jia, Zeng-yong;Jia, Xiao-bin
    • Journal of Ginseng Research
    • /
    • v.40 no.3
    • /
    • pp.269-277
    • /
    • 2016
  • Background: The findings of currently available studies are not consistent with regard to the association between the risk of cancer and ginseng consumption. Therefore, we aimed to evaluate this association by conducting a meta-analysis of different studies. Methods: To systematically evaluate the effect of ginseng consumption on cancer incidence, six databases were searched, including PubMed, Ovid Technologies, Embase, The Cochrane Library, China National Knowledge Infrastructure, and Chinese VIP Information, from 1990 to 2014. Statistical analyses based on the protocol employed for a systematic review were conducted to calculate the summary relative risks (RRs) and 95% confidence intervals (CIs). Results: We identified nine studies, including five cohort studies, three case-control studies, and one randomized controlled trial, evaluating the association between ginseng consumption and cancer risk; these studies involved 7,436 cases and 334,544 participants. The data from the meta-analysis indicated a significant 16% lower risk of developing cancer in patients who consumed ginseng (RR = 0.84, 95% CI = 0.76-0.92), with evidence of heterogeneity (p = 0.0007, $I^2$ = 70%). Stratified analyses suggested that the significant heterogeneity may result from the incidence data for gastric cancer that were included in this study. Publication bias also showed the same result as the stratified analyses. In addition, subgroup analyses for four specific types of cancer (colorectal cancer, lung cancer, gastric cancer, and liver cancer) were also performed. The summary RRs for ginseng intake versus no ginseng consumption were 0.77 for lung cancer, 0.83 for gastric cancer, 0.81 for liver cancer, and 0.77 for colorectal cancer. Conclusion: The findings of this meta-analysis indicated that ginseng consumption is associated with a significantly decreased risk of cancer and that the effect is not organ specific.

Comparison between Possibilistic c-Means (PCM) and Artificial Neural Network (ANN) Classification Algorithms in Land use/ Land cover Classification

  • Ganbold, Ganchimeg;Chasia, Stanley
    • International Journal of Knowledge Content Development & Technology
    • /
    • v.7 no.1
    • /
    • pp.57-78
    • /
    • 2017
  • There are several statistical classification algorithms available for land use/land cover classification. However, each has a certain bias or compromise. Some methods like the parallel piped approach in supervised classification, cannot classify continuous regions within a feature. On the other hand, while unsupervised classification method takes maximum advantage of spectral variability in an image, the maximally separable clusters in spectral space may not do much for our perception of important classes in a given study area. In this research, the output of an ANN algorithm was compared with the Possibilistic c-Means an improvement of the fuzzy c-Means on both moderate resolutions Landsat8 and a high resolution Formosat 2 images. The Formosat 2 image comes with an 8m spectral resolution on the multispectral data. This multispectral image data was resampled to 10m in order to maintain a uniform ratio of 1:3 against Landsat 8 image. Six classes were chosen for analysis including: Dense forest, eucalyptus, water, grassland, wheat and riverine sand. Using a standard false color composite (FCC), the six features reflected differently in the infrared region with wheat producing the brightest pixel values. Signature collection per class was therefore easily obtained for all classifications. The output of both ANN and FCM, were analyzed separately for accuracy and an error matrix generated to assess the quality and accuracy of the classification algorithms. When you compare the results of the two methods on a per-class-basis, ANN had a crisper output compared to PCM which yielded clusters with pixels especially on the moderate resolution Landsat 8 imagery.

The Study for NHPP Software Reliability Model based on Chi-Square Distribution (카이제곱 NHPP에 의한 소프트웨어 신뢰성 모형에 관한 연구)

  • Kim, Hee-Cheul
    • Journal of the Korea Society of Computer and Information
    • /
    • v.11 no.1 s.39
    • /
    • pp.45-53
    • /
    • 2006
  • Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, Goel-Okumoto and Yamada-Ohba-Osaki model was reviewed, proposes the $x^2$ reliability model, which can capture the increasing nature of the failure occurrence rate per fault. 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, SYS2(Allen P.Nikora and Michael R.Lyu), for the sake of proposing shape parameter of the $x^2$ distribution using the degree of freedom, was employed. This analysis of failure data compared with the $x^2$ model and the existing model using arithmetic and Laplace trend tests, Kolmogorov test is presented.

  • PDF

Coordinate Accuracy Comparison of Online GPS Data Processing Services (온라인 GPS 자료처리 서비스의 좌표 정확도 비교분석)

  • Won, Ji-Hye;Son, Eun-Seong;Park, Kwan-Dong
    • Journal of Korean Society for Geospatial Information Science
    • /
    • v.18 no.4
    • /
    • pp.31-39
    • /
    • 2010
  • In this study, the performance of the online GPS processing services provided by diverse institutions was compared so that domestic GPS users in geodesy and surveying can easily get precise coordinates using those services. In order to evaluate the accuracy of each online GPS processing service, we calculated coordinates of seven GPS permanent stations located in Korea and foreign countries using APPS, CSRS-PPP, AUSPOS and OPUS. And the results were compared with published coordinates by IERS and National Geographic Information Institute. In the cases of foreign stations, the mean value of the horizontal errors was 9.3 mm and the descending order of accuracies was APPS, AUSPOS, OPUS and CSRS-PPP. In the cases of Korean stations, the mean value of the horizontal errors was 37.6 mm, although the order of accuracy was similar to the foreign cases; AUSPOS, APPS, OPUS and CSRS-PPP. Also, the average value of 3-D errors in Korean cases was about 3 cm larger than that of foreign cases and a bias of 3 cm was observed in the north direction.

Abundance Estimation of the Finless Porpoise, Neophocaena phocaenoides, Using Models of the Detection Function in a Line Transect (Line Transect에서 발견율함수 추정에 사용되는 모델에 따른 상괭이, Neophocaena phocaenoides의 자원개체수 추정)

  • Park, Kyum-Joon;Kim, Zang-Geun;Zhang, Chang-Ik
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.40 no.4
    • /
    • pp.201-209
    • /
    • 2007
  • Line transect sampling in a sighting survey is one of most widely used methods for assessing animal abundance. This study applied distance data, collected from three sighting surveys using line transects for finless porpoise that were conducted in 2004 and 2005 off the west coast of Korea, to four models (hazard-rate, uniform, half-normal and exponential) that can use a variety of detection functions, g (x). The hazard-rate model, a derived model for the detection function, should have a shoulder condition chosen using the AIC (Akaike Information Criterion), as the most suitable model. However, it did not describe a shoulder shape for the value of g(x) near the track tine and underestimated g (x), just as the exponential model did. The hazard-rate model showed a bias toward overestimating the densities of finless porpoises with a higher coefficient of variation (CV) than the other models did. The uniform model underestimated the densities of finless porpoise but had the lowest CV. The half-normal model described a detection function with a shape similar to that of the uniform model. The half-normal model was robust for finless porpoise data and should be able to avoid density underestimation. The estimated abundance of finless porpoise was 3,602 individuals (95% CI=1,251-10,371) inshore in 2005 and 33,045 individuals (95% CI=24,274-44,985) offshore in 2004.

A redistribution model for spatially dependent Parrondo games (공간의존 파론도 게임의 재분배 모형)

  • Lee, Jiyeon
    • Journal of the Korean Data and Information Science Society
    • /
    • v.27 no.1
    • /
    • pp.121-130
    • /
    • 2016
  • An ansemble of N players arranged in a circle play a spatially dependent Parrondo game B. One player is randomly selected to play game B, which is based on the toss of a biased coin, with the amount of the bias depending on states of the selected player's two nearest neighbors. The player wins one unit with heads and loses one unit with tails. In game A' the randomly chosen player transfers one unit of capital to another player who is randomly chosen among N - 1 players. Game A' is fair with respect to the ensemble's total profit. The games are said to exhibit the Parrondo effect if game B is losing and the random mixture game C is winning and the reverse-Parrondo effect if game B is winning and the random mixture game C is losing. We compute the exact mean profits for games B and C by applying a state space reduction method with lumped Markov chains and we sketch the Parrondo and reverse-Parrondo regions for $3{\leq}N{\leq}6$.

Large Signal Unified Model for GaAs pHEMT using Modified Curtice Model (새롭게 수정된 Curtice 모델을 이용한 GaAs pHEMT 대신호 통합모델 구축)

  • 박덕종;염경환;장동필;이재현
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.12 no.4
    • /
    • pp.551-561
    • /
    • 2001
  • In this paper, the large signal unified model is established for H4O GaAs pHEMT of GEC-Marconi using modified Curtice model. This unified model includes DC characteristic, small signal, and noise characteristic as various bias. Particularly, the model can simply and physically explain trans-conductance $(g_m)$ of pHEMT using modified Curtice model, and can tell the difference $g_m$, $R_ds$ at DC and these at AC through inclusion of internal RF-choke. The results of the established model built up using SDD in HP-Eessof show good agreement to the S/W measured data in DC, small signal, and noise characteristic. This model can also be applied to various computer aided analysis, such as linear simulation, 1-tone harmonic balance simulation, and multi-tone harmonic balance simulation, so the LNA(Low Noise Amplifier), oscillator, and mixer design has been shown using this model library.

  • PDF

The Spatial Structure of the Production of Technological Knowledge in the Korean Photonics Industry (한국 광산업(光産業) 기술지식 창출의 공간구조)

  • Lim, Young-Hun;Park, Sam-Ock
    • Journal of the Korean Geographical Society
    • /
    • v.44 no.3
    • /
    • pp.355-371
    • /
    • 2009
  • The purpose of this study is to investigate the spatial structure of the production of technological knowledge in the Korean photonics industry. Patent data were used as a proxy of knowledge production. The data were gathered by keywords among the registered patents which were applied from 1996 to 2007. The photonics industry patents registered at United States Patent Trademark Office(USPTO) show that Korea and Taiwan, as a latecomer, have rapidly increased. The photonics industry patents registered at Korean Intellectual Property Office(KIPO) were analyzed by type of application: single-applicant and co-applicant patents. The analysis of single-applicant patents shows that technological knowledge in the Korean photonics industry has been produced mainly in Seoul, Suwon, and Daejeon. The degree of spatial bias, however, has been slightly decreased during the study period. Above-mentioned regions are also main centers in the analysis of co-applicant patents, but the forms of inter-regional cluster and network are different over time. It is because agents participating in co-applicant patents are diverse and increased. Furthermore, it seems that policies, such as the improvement of the infrastructure of ICT, the promotion of the photonics industry and the industry-university-institute collaboration, are very influential.

The Representation of Cancer Risk by Korean Health Journalism: Comparing the Crude Rates of 10 Cancers to the Amount of Cancer News in the Three Major Newspapers(1990-2010) (10대암 조발생률과 신문 보도량의 비교: 3대 일간지 보도(1990년~2010년)를 중심으로)

  • Ju, Youngkee;Jeong, Da-Eun;You, Myoungsoon
    • Korean Journal of Health Education and Promotion
    • /
    • v.30 no.5
    • /
    • pp.201-210
    • /
    • 2013
  • Objectives: The public relies on the news media to understand health risks. To examine the surveillance function of Korean health journalism, this study compared the rank-order of the 10 most frequently diagnosed cancers with that of the 10 cancers most frequently covered by three major Korean newspapers. Methods: News stories published between 1999 and 2010 by the Chosun-Ilbo, Joong-Ang-Ilbo, and Dong-A-Ilbo were examined. Data on cancer incidence were collected using the epidemiological data published by a governmental public health institution. To compare the level of the crude rates and the amount of news coverage, rank-order correlation tests and regression analyses were employed. Results: A reduction in the rank-ordered correlation coefficient was observed despite an increase in the overall number of cancer news stories released. The significance of the correlation disappeared after 2006. The big difference of the rank order between the crude rate and the amount of news coverage was observed in the cancer of breast, uteri, thyroid, and gallbladder/biliary. Finally, the three newspapers did not follow the amount change in stomach, lung, liver, and uterine cervix cancer. The four cancers' rank orders of crude rate were lowering, signifying a reduction of the comparative dangerousness of the four cancers. Conclusions: The news media's customization of news content and the negative bias in journalism are suggested as possible influences on the news media's inaccurate representation of cancer risk.

An improved 1D-model for computing the thermal behaviour of concrete dams during operation. Comparison with other approaches

  • Santillan, D.;Saleteb, E.;Toledob, M.A.;Granados, A.
    • Computers and Concrete
    • /
    • v.15 no.1
    • /
    • pp.103-126
    • /
    • 2015
  • Thermal effects are significant loads for assessing concrete dam behaviour during operation. A new methodology to estimate thermal loads on concrete dams taking into account processes which were previously unconsidered, such as: the evaporative cooling, the night radiating cooling or the shades, has been recently reported. The application of this novel approach in combination with a three-dimensional finite element method to solve the heat diffusion equation led to a precise characterization of the thermal field inside the dam. However, that approach may be computationally expensive. This paper proposes the use of a new one-dimensional model based on an explicit finite difference scheme which is improved by means of the reported methodology for computing the heat fluxes through the dam faces. The improved model has been applied to a case study where observations from 21 concrete thermometers and data of climatic variables were available. The results are compared with those from: (a) the original one-dimensional finite difference model, (b) the Stucky-Derron classical one-dimensional analytical solution, and (c) a three-dimensional finite element method. The results of the improved model match well with the observed temperatures, in addition they are similar to those obtained with (c) except in the vicinity of the abutments, although this later is a considerably more complex methodology. The improved model have a better performance than the models (a) and (b), whose results present larger error and bias when compared with the recorded data.