• Title/Summary/Keyword: Statistical hypothesis

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P-value significance level test for high-performance steel fiber concrete (HPSFC)

  • Abubakar, Abdulhameed U.;Akcaoglu, Tulin;Marar, Khaled
    • Computers and Concrete
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    • v.21 no.5
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    • pp.485-493
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    • 2018
  • Statistical analysis has found useful application in the design of experiments (DOE) especially optimization of concrete ingredients however, to be able to apply the concept properly using computer aided applications there has to be an upper and lower limits of responses fed to the system. In this study, the production of high-performance steel fiber concrete (HPSFC) at five different fiber addition levels by volume with two aspect ratios of 60 and 83 were studied under two curing methods completely dry cured (DC) and moist cured (MC) conditions. In other words, this study was carried out for those limits based on material properties available in North Cyprus. Specimens utilized were cubes 100 mm size casted and cured for 28 days and tested for compressive strength. Minitab 18 statistical software was utilized for the analysis of results at a 5 per cent level of significance. Experimentally, it was observed that, there was fluctuation in compressive strength results for the two aspect ratios and curing regimes. On the other hand P-value hypothesis evaluation of the response showed that at the stated level of significance, there was a statistically significant difference between dry and moist curing conditions. Upper and lower limit values were proposed for the response to be utilized in DOE for future studies based on these material properties. It was also suggested that for a narrow confidence interval and accuracy of the system, future study should increase the sample size.

Identifying the Chickens-Eggs Statistical Lead-Lag Dilemma (닭-달걀 간 통계적 인과성 논란의 판별)

  • Kim, Tae Ho;Kim, Min Jeong;Lee, Jeen Woan
    • The Korean Journal of Applied Statistics
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    • v.26 no.3
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    • pp.401-411
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    • 2013
  • This study investigates the controversial chickens-eggs dilemma and empirically performs statistical tests to examine if there exists a causality between them. Granger and Hsiao tests are applied to both level and stationary variables to identify the lead-lag relationships. Each of these test is found to have the robust result where the causality runs from eggs to chickens; in addition, the explanatory power of one variable in variations of the other appears to remain time invariant. The outcome is proved to be valid as the hypothesis test for no structural change in their relationship fails to be rejected.

Statistical Methods for the Use of Infiltration and Inflow as Performance Index in Sewer Rehabilitation Works (하수관거정비사업에서 침입수.유입수 성과지표 활용을 위한 통계적 방법론에 관한 연구)

  • Kim, Hyung-Joon;Park, Kyoo-Hong
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.5
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    • pp.617-628
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    • 2010
  • The operation performance of sewer rehabilitation projects conducted with Build-Transfer- Lease contract in Korea will be evaluated using the index of infiltration and inflow (I/I). Though I/I obtained at the fourth year should be initially evaluated based on the I/I values observed for the previous three years after the completion of sewer construction, the concrete methodology have not been proposed to rely on the so called 'performance evaluation committee'. This study suggests two statistical methodology to evaluate the I/I performance; the confidence interval method and the hypothesis-testing method. Assumed ten I/I values in each year for 20 years are used in this study. Two cases are analyzed and compared; case I to use as control data all I/I values for all years obtained before the evaluation year and case II to use I/I values for only 3 years before the evaluation year. As a result, case II tends to have relatively higher scores than case I, reflecting the low mean I/I values at the initial years.

PREDICTION OF THE DETECTION LIMIT IN A NEW COUNTING EXPERIMENT

  • Seon, Kwang-Il
    • Journal of The Korean Astronomical Society
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    • v.41 no.4
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    • pp.99-107
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    • 2008
  • When a new counting experiment is proposed, it is crucial to predict whether the desired source signal will be detected, or how much observation time is required in order to detect the signal at a certain significance level. The concept of the a priori prediction of the detection limit in a newly proposed experiment should be distinguished from the a posteriori claim or decision whether a source signal was detected in an experiment already performed, and the calculation of statistical significance of a measured source signal. We formulate precise definitions of these concepts based on the statistical theory of hypothesis testing, and derive an approximate formula to estimate quickly the a priori detection limit of expected Poissonian source signals. A more accurate algorithm for calculating the detection limits in a counting experiment is also proposed. The formula and the proposed algorithm may be used for the estimation of required integration or observation time in proposals of new experiments. Applications include the calculation of integration time required for the detection of faint emission lines in a newly proposed spectroscopic observation, and the detection of faint sources in a new imaging observation. We apply the results to the calculation of observation time required to claim the detection of the surface thermal emission from neutron stars with two virtual instruments.

Value-Relevance of R&D and Ad expenditures in the Medical Industry : Medical Precision and Medicine Industry Case (의료관련 산업의 연구개발비와 광고선전비 지출이 기업가치에 미치는 영향 (의료정밀과 의약품 산업을 중심으로))

  • Cho, Duk-Young;Choi, Soo-Hyung
    • Korea Journal of Hospital Management
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    • v.11 no.3
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    • pp.1-18
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    • 2006
  • The purpose of this study is to analyze the relationship between intangible asset items and company value by empirical research in the medical industry, which may enhance usefulness of the results of other empirical research on intangible asset and company value. In order to attain the purpose of this study, the stock price is taken as the independent variable and all of intangible asset items reported to a balance sheet except the development expenditures and other development expenditures, and advertisement expenses, ordinary research & development expenditures reported on the income statement are taken as the dependent variables. In the following, I carried out four meaningful results from the analysis. First, research hypothesis 1; Book value of intangible asset reported in balance sheet bears positive relationship with company value shows that development expenditures 1 variable gives positive association in a significant level while a group of \10,000-above-company shows no relationship with company value, the other group of below-\10,000-company supports a consistently significant association. All this considering, we have to keep in mind that lack of prudence may leads to wrong results when we try to analyze. Second, research hypothesis 2; Intangible asset and other intangible asset expenditures reported on the income statement gives positive effect on company value shows that R&D accounts variables give insignificance in a statistical level to all company, including entire group, \10,000-above and below consistently. These results testify that current accounting system is valid. Third, in the case of other intangible asset, it requires further examination of current KAS because statistical results show negatively significant value or insignificant value in a statistical level. That means the more intangible assets, the less company value or nothing. Last, in the case of advertisement expenditure variables of above-\10,000 and entire company shows insignificances in a statistical level consistently while below-\10,000-company shows significant result coherently. We should regard accounting information on the advertisement expenditures of \10,000-below-company with caution. The results of this study provide controversial points whether intangible asset items reported on B/S, excluding development expenditures, should be regarded as asset. To facilitate the utility of accounting information on intangible asset, it seems necessary to regard advertisement expenditures reported on I/S as asset accounts. There are further arguments on the way of dealing with intangible asset under KAS that might be considered.

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The Effect of Organizational Culture and Job Environment Characteristics Perceived by Organization Members on Job Satisfaction

  • Kim, Moon Jun
    • International Journal of Internet, Broadcasting and Communication
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    • v.12 no.4
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    • pp.156-165
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    • 2020
  • We study empirically analyzed the final 216 copies of the responses from SME organization members in Seoul and Gyeonggi regions using statistical programs of SPSS24.0 and AMOS 24.0. In other words, the effect of job satisfaction on the organizational culture and job environment characteristics perceived by members of the organization, and the relationship between job satisfaction and job performance is shown as follows. First, the organizational culture of consensus, development, hierarchy, and rationality was statistically significant in job satisfaction. Therefore, the hypothetical one-man organizational culture was adopted by showing a positive (+) effect on job satisfaction. Second, job environment characteristics such as autonomy in job performance, compensation system, physical environment, and human environment had a positive effect on job satisfaction. That is, the job environment characteristics of hypothesis 2 were adopted as a positive (+) influence relationship on organizational satisfaction. Third, job satisfaction was expressed as a positive (+) influence relationship with job performance, so hypothesis 3 was adopted. As a result of this study, the higher the organizational member's perception of organizational culture and job environment characteristics is, the higher the job satisfaction is, and the improvement in job satisfaction is meaningful in that it provides theoretical and practical implications that indicate job performance.

An Emperical Study on Activation of uTradehub (uTradeHub 활성화 방안에 관한 실증 분석)

  • CHOI, Tae-Kwang;RYU, Seung-Yeal
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.71
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    • pp.217-243
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    • 2016
  • As the rapid development of IT and the internet changed the trading method from the traditional offline transaction into the online e-Trading, the international documentation standards, the eUCP and the domestic laws and legislations have been established, adapting to the new e-Trading environment. This study was conducted to analyze the factors which affect the use of uTradeHub on the domestic trading companies and trade-related organizations and suggest how to activate e-Trading. To do this, classify the users into the enterprises and the trade-related organizations, set up the hypothesis of the study with the measurement variables of the user convenience, the new service, the system suitability and the legislation environment and carry out a survey targeting the trading companies and the trade-related offices to do an actual proof analysis. The analysis was performed by using the statistical program, SPSS IBM22.0, and the study hypothesis was tested by the multiple regression analysis methodology. The test result showed that the trading companies set a high value on the user convenience, the new service and the legislation environment of uTradeHub, meanwhile the trade-related organizations regarded the system security and reliability, the user convenience and the legislation environment as the major affecting factor on the use of uTradeHub.

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The Null Distribution of the Likelihood Ratio Test for a Mixture of Two Gammas

  • Min, Dae-Hee
    • Journal of the Korean Data and Information Science Society
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    • v.9 no.2
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    • pp.289-298
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    • 1998
  • We investigate the distribution of likelihood ratio test(LRT) of null hypothesis a sample is from single gamma with unknown shape and scale against the alternative hypothesis a sample is from a mixture of two gammas, each with unknown scale and unknown (but equal) scale. To obtain stable maximum likelihood estimates(MLE) of a mixture of two gamma distributions, the EM(Dempster, Laird, and Robin(1977))and Modified Newton(Jensen and Johansen(1991)) algorithms were implemented. Based on EM, we made a simple structure likelihood equation for each parameter and could obtain stable solution by Modified Newton Algorithms. Simulation study was conducted to investigate the distribution of LRT for sample size n = 25, 50, 75, 100, 50, 200, 300, 400, 500 with 2500 replications. To determine the small sample distribution of LRT, I considered the model of a gamma distribution with shape parameter equal to 1 + f(n) and scale parameter equal to 2. The simulation results indicate that the null distribution is essentially invariant to the value of the shape parameter. Modeling of the null distribution indicates that it is well approximated by a gamma distribution with shape parameter equal to the quantity $0.927+1.18/\sqrt{n}$ and scale parameter equal to 2.16.

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Sensibility Estimation Analysis about Treatment Circumstance of Children with Autism (자폐성 장애아동 치료환경에 대한 감성평가분석)

  • Cho, Myoung-Min;Jung, A-Young;Kong, Soon-Ku
    • Korean Institute of Interior Design Journal
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    • v.23 no.5
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    • pp.86-95
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    • 2014
  • This study verified a hypothesis "treatment circumstance that considers character of children with autism has an effect on emotion stability", and I set the final aim to suggest emotional design elements according to treatment program and also to construct basic data about study of treatment circumstance of children with autism. So I conduct a survey of teachers of nine centers for the disabled about "satisfaction about treatment circumstance, importance of design elements of treatment circumstance that increase children's with autism stability, sensibility estimation about treatment circumstance" and committed statistical analysis. As the results, emotional design elements that have to be improved are the wall finishing material, the color of the wall, and the artificial lighting. The color of the wall has an effect on importance of treatment circumstance and emotional design elements influence 47% to satisfaction of treatment circumstance. It get the positive result about the hypothesis "treatment circumstance that considers character of children with autism has an effect on emotion stability".

Bootstrap inference for covariance matrices of two independent populations (두 독립 모집단의 공분산 행렬에 대한 붓스트랩 추론)

  • 김기영;전명식
    • The Korean Journal of Applied Statistics
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    • v.4 no.1
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    • pp.1-11
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    • 1991
  • It is of great interest to consider the homogeniety of covariance matrices in MANOVA of discriminant analysis. If we lock at the problem of testing hypothesis, H : $\Sigma_1 = \Sigma_2$ from an invariance point of view where $\Sigma_i$ are the covariance matrix of two independent p-variate distribution, the testing problem is invariant under the group of nonsingular transformations and the hypothesis becomes H : $\delta_1 = \delta_2 = \cdots = \delta_p = 1$ where $\delta = (\delta_1, \delta_2, \cdots, \delta_p)$ is a vector of latent roots of $\Sigma$. Bias-corrected estimators of eigenvalues and sampling distribution of the test statistics proposed are obtained. Pooled-bootstrap method also considered for Bartlett's modified likelihood ratio statistics.

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