• Title/Summary/Keyword: Test of hypothesis

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A Test of Fit for Inverse Gaussian Distribution Based on the Probability Integration Transformation (확률적분변환에 기초한 역가우스분포에 대한 적합도 검정)

  • Choi, Byungjin
    • The Korean Journal of Applied Statistics
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    • v.26 no.4
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    • pp.611-622
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    • 2013
  • Mudholkar and Tian (2002) proposed an entropy-based test of fit for the inverse Gaussian distribution; however, the test can be applied to only the composite hypothesis of the inverse Gaussian distribution with an unknown location parameter. In this paper, we propose an entropy-based goodness-of-fit test for an inverse Gaussian distribution that can be applied to the composite hypothesis of the inverse Gaussian distribution as well as the simple hypothesis of the inverse Gaussian distribution with a specified location parameter. The proposed test is based on the probability integration transformation. The critical values of the test statistic estimated by simulations are presented in a tabular form. A simulation study is performed to compare the proposed test under some selected alternatives with Mudholkar and Tian (2002)'s test in terms of power. The results show that the proposed test has better power than the previous entropy-based test.

Importing and Firm Productivity: Evidence from Korean Manufacturing Firms

  • Heechul Min
    • Journal of Korea Trade
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    • v.26 no.3
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    • pp.102-116
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    • 2022
  • Purpose - This paper empirically investigates the relationship between firm productivity and importing intermediate inputs in the Korean manufacturing sector. Design/methodology - This paper tests the two related hypotheses on the relationship between importing and productivity for a sample of Korean manufacturing firms. We test the self-selection hypothesis by comparing pre-entry levels of productivity between importers and non-importers. We test the learning-by-importing hypothesis by employing propensity score matching with differencein-differences approach. Findings - Future importers are more productive than future non-importers years before they start to import, which supports the self-selection hypothesis. In contrast, there is no strong evidence for learning-by-importing. Originality/value - This paper is the first study to explore the relationship between importing and firm-level productivity for Korean firms. The results have an important implication on trade policies to lower or raise trade barriers in imported inputs.

The Stomach's Communication with Its Related Acupoints, and the "Intelligent Tissue" Hypothesis

  • Kovich, Fletcher
    • Journal of Acupuncture Research
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    • v.36 no.1
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    • pp.21-27
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    • 2019
  • Background: The intelligent tissue hypothesis holds that an organ's states (be it normal function or stressed states) are reflected in real time at its related acupuncture points (acupoints), causing physical, real-time changes in the local tissue. The experiment was devised to test this. Methods: The patient drank chilled water while the impedance at 6 stomach-related acupoints was monitored in real time (sample rate of 1 kHz). Any changes in the local tissue at the acupoints ought to be reflected in changes in the impedance. Results: The impedance at every test acupoint showed a response to the chilled water being ingested. Also, the duodenal pacesetter and the stomach's slow waves were clearly visible in the impedance pattern at all the acupoints. Conclusion: Hence, many separate details of the stomach's function were reflected at these acupoints. The duodenal features were consistent with the traditional indications for these acupoints, which are noted to be able to treat intestinal conditions. Therefore, the results were consistent with the hypothesis and also provided a possible explanation for how the use of these acupoints is able to treat intestinal conditions.

The Effects of General Coordinative Manipulation Interventions on the Postural Control (전신조정술 중재가 자세조절에 미치는 효과)

  • Moon, Sang-Eun;Kim, Mi-Hwa;Ju, Wang-Suck;Lee, Su-Hong;Oh, Chang-Sun;Choi, Min-Ho;Jung, Woong-Chae
    • Journal of Acupuncture Research
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    • v.26 no.5
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    • pp.137-149
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    • 2009
  • Objectives : This study was designed to analyze whether General Coordinative Manipulation(GCM) Intervention could have effects on the balanced restoration of asymmetrical posture. Methods : Sixty eight(68) healthy volunteers(1st hypothesis: 46, 2nd hypothesis 22) participated in two GCM interventions, which have been performed 2 times a week for 3 weeks. The Global Postural System(GPS) Unit was used to measure the posture, and measurements were performed before and after the application of each intervention group. A paired t-test and wilcoxon test were used to determine the statistical significance. Results : The outcome of examining the hypothesis is as follows: 1. The 1st hypothesis: It has been proved that GCM Intervention, which coordinates the flexion type of upper extremity and the extension type of lower extremity, excluding self-care, shows the efficiency in treatment on more than two aspects of 3 parts: anterior, posterior and lateral postures, and the effects on more than 3 of 4 body types. 2. The 2nd hypothesis: It has been proved that GCM Intervention, which coordinates the flexion type of lower extremity and the extension type of upper extremity, excluding self-care, shows the treatment in efficiency on more than two aspects of 3 parts: anterior, posterior and lateral postures, and the effects on more than 2 of 3 body types. Conclusions : GCM intervention programs on the two hypothesis groups have an affect on the balanced restoration of the postural control system.

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Effects of a Sensory Stimulation on Weight Gain, Behavioral State, and Physiological Responses in Premature Infants (감각자극이 미숙아의 체중 증가, 행동상태 및 생리적 반응에 미치는 영향)

  • 송희승;신희선
    • Journal of Korean Academy of Nursing
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    • v.31 no.4
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    • pp.703-711
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    • 2001
  • Purpose: The purpose of this study was to examine the effects of sensory stimulation on premature infants. Method: Thirty three premature infants admitted to NICU of D University Hospital in C city were randomly assigned in two groups (Experimental group: 16, Control group:17). For the experimental group, tactile and kinesthetic stimulation developed by Dr. Field was applied 2 times a day for 10 days. Behavioral state was measured using the Anderson Behavioral State Scale (ABSS). Heart rate, respiration, and oxygen saturation were obtained for each infant before and after sensory stimulation. Hypothesis testing was done using the $\chi$$^2$- test, student t-test, and repeated measures of ANOVA. Result: Hypothesis 1: There was a significant difference in the daily body weight gain between experimental and control group (F= 40.77, p= .0001). Hypothesis 2: There was a significant difference in the frequency of 'inactive awake state' between two groups ($\chi$$^2$= 39.778, p= .001). Hypothesis 3: There were significant differences in the mean of heart rate and $O_2$saturation between two groups (t= -2.174, p= .037; t= 3.080, p= .005). However, there was no significant difference in the mean of respiration rate between two groups (t= -1.966, p= .581). Conclusion: The effectiveness of a sensory stimulation on weight gain and behavioral state in premature infants was supported. Further study is recommended to develop a sensory stimulation method as an independent nursing intervention for premature infant.

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A Test of the Underlying Processes of the Price-Induced Quality Perception

  • Suk, Kwan-Ho
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.2
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    • pp.47-64
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    • 2008
  • It is well known that consumer's quality perception is strongly affected by price. Higher priced products tend to be perceived to have better quality than lower priced products although the objective product quality is the same. However, it is less known the process through which quality perception is affected by price cues. The existing literature suggests three potential hypotheses (i.e., the selectiveprocessing hypothesis, the selective interpretation hypothesis, and the representativeness heuristic hypothesis) that explain the underlying processes of the price-induced quality perception. The current research tests among the three competing hypotheses and also examines the role of consumer knowledge as a moderating factor. An experiment was conducted to test the moderating role of the knowledge in the price-quality relationship and to investigate the underlying process. The results indicate that theinfluence of price on perceived quality differs between novices and experts. Expert consumers' quality perception is not significantly influenced by price and this finding is consistent with the extant literature. On the other hand, novice consumers' quality perception is affected by price and the tests on the underlying process support for the representativeness heuristic hypothesis. Novice consumers assess that a high-priced brand should have good product quality due to the belief that high (low) price brands represent better (worse) brand quality and such a representativeness heuristic occurs without involving selective attention or selective interpretation price-consistent information.

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Monte Carlo simulation for verification of nonparametric tests used in final status surveys of MARSSIM at decommissioning of nuclear facilities

  • Sohn, Wook;Hong, Eun-hee
    • Nuclear Engineering and Technology
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    • v.53 no.5
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    • pp.1664-1675
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    • 2021
  • In order to verify the statistical performance of the nonparametric tests used in the MARSSIM approach, all plausible contamination distribution types that can be encountered in a survey area should be investigated. As the first of such investigations, this study aims to perform the verification for normal distribution of the contamination in a survey area by simulating the collection of random samples from it through the Monte Carlo simulation. The results of the simulations conducted for a total of 81 simulation cases showed that Sign test and WRS test both exhibited an excellent statistical performance: 100% for the former and 98.8% for the latter. Therefore, in final status surveys of the MARSSIM approach, a high statistical performance can be expected in applying the nonparametric hypothesis tests to survey areas whose net contamination can be assumed to be normally distributed.

The Effects of Aerobic Exercise on Health Status of the Patients with Essential Hypertension (유산소운동이 본태성 고혈압 대상자의 건강상태에 미치는 효과)

  • Jeon, Eun-Young
    • The Korean Journal of Rehabilitation Nursing
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    • v.6 no.2
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    • pp.173-182
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    • 2003
  • Purpose: This study was conducted to evaluate the effects of aerobic exercise on health status with essential hypertension. Method: A non-equivalent control group design was used. For the experimental group, aerobic exercise was given by researcher at one health center in Daegu. Test for hypothesis was done by $X^2$-test t-test, paired t-test, and unpaired t-test. Result: There were significant differences in systolic, diastolic, and MAP between two groups. There were significant differences in body weight, BMI, and body composition between two groups. Hypothesis 3 was partially supported that the score of health status and physical function of experimental group were significantly higher than that of control group. Conclusion: Findings indicated that this study would contribute to application of aerobic exercise as nursing intervention for the people with high blood pressure.

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The Effects of Science Inquiry Learning Applying Open- Ended Hypothesis-Testing Learning Model: On the ‘Metals and Their Applications’ Unit in Chemistry (개방적 가설검증 학습모형을 적용한 과학 탐구학습의 효과:화학 I ‘금속과 그 이용’ 단원을 중심으로)

  • Jeong, Dae-Hong;Bang, Jeong-A;Choi, Chui-Im;Choi, Won-Ho
    • Journal of the Korean Chemical Society
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    • v.50 no.5
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    • pp.385-393
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    • 2006
  • In this study, we analyzed the effects of science inquiry learning that applies open-ended hypothesis-testing learning model in a high school chemistry class of grade 11 in respect of science process skills, science-related attitude, and appreciation towards science class by cognitive level. Open-ended science inquiry learning activities on Metals and their applications unit in Chemistry I were developed and applied to the treatment groups while the conventional science activities were applied to the control groups. Four classes of 92 students in a high school located in Seoul were assigned into the treatment and control groups, respectively. According to the results in the test of science process skills, the students treated with the alternative experiments emphasizing open-ended hypothesis-testing obtained higher scores in experimental design, data conversion and description, and hypothesis test than those with conventional experiments but not in problem cognition and definition and hypothesis fixing'. There was negative effect on science-related attitude due to increased roles and tasks in the open-ended science inquiry learning activities.

A Comparison of Scientists' and Students' Responses to Discrepant Event and Alternative Hypothesis in the Conceptual Change Processes from the Phlogiston Theory to the Oxygen Theory (플로지스톤설에서 산소설로의 개념 변화 과정에서 변칙 사례와 대안 가설에 대한 과학자들과 학생들의 반응 비교)

  • Noh, Tae-Hee;Yun, Jeong-Hyun;Kang, Hun-Sik;Kang, Suk-Jin
    • Journal of The Korean Association For Science Education
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    • v.26 no.7
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    • pp.798-804
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    • 2006
  • In this study, we investigated students' responses to a discrepant event and an alternative hypothesis which had been presented in the conceptual change processes from the phlogiston theory to the oxygen theory, and compared them with scientists' responses. The data concerning scientists' responses to the discrepant event and the alternative hypothesis were gathered from the relevant literature on the history of science. Subjects were 148 eighth graders who possessed the target misconception about combustion through a preconception test. After having been presented with the discrepant event and the alternative hypothesis, students were asked to respond to the test of response to discrepant event. Although similar types of responses were obtained from both scientists and students, there was also a clear difference. Scientists tended to focus on explaining the problems of the discrepant event, whereas students tended to ignore and/or exclude the discrepant event in order to maintain their previous beliefs. Only a few students were also found to change their beliefs after having been presented with the alternative hypothesis.