• Title/Summary/Keyword: sample variance

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Empirical Analysis on Rao-Scott First Order Adjustment for Two Population Homogeneity test Based on Stratified Three-Stage Cluster Sampling with PPS

  • Heo, Sunyeong
    • Journal of Integrative Natural Science
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    • v.7 no.3
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    • pp.208-213
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    • 2014
  • National-wide and/or large scale sample surveys generally use complex sample design. Traditional Pearson chi-square test is not appropriate for the categorical complex sample data. Rao-Scott suggested an adjustment method for Pearson chi-square test, which uses the average of eigenvalues of design matrix of cell probabilities. This study is to compare the efficiency of Rao-Scott first order adjusted test to Wald test for homogeneity between two populations using 2009 Gyeongnam regional education offices's customer satisfaction survey (2009 GREOCSS) data. The 2009 GREOCSS data were collected based on stratified three-stage cluster sampling with probability proportional to size. The empirical results show that the Rao-Scott adjusted test statistic using only the variances of cell probabilities is very close to the Wald test statistic, which uses the covariance matrix of cell probabilities, under the 2009 GREOCSS data based. However it is necessary to be cautious to use the Rao-Scott first order adjusted test statistic in the place of Wald test because its efficiency is decreasing as the relative variance of eigenvalues of the design matrix of cell probabilities is increasing, specially more when the number of degrees of freedom is small.

A Sample Design for Intestinal Parasitic Infection Survey (기생충 감염실태조사를 위한 표본설계)

  • Ryu Jea-Bok;Lee Seung-Joo;Jun Sung-Rae
    • The Korean Journal of Applied Statistics
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    • v.18 no.1
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    • pp.27-41
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    • 2005
  • We made a new sample design for intestinal parasitic infection survey in 2004. We used the 10% sample survey data of 2000 population and housing census as a survey population. Since the infection rates of intestinal parasitics are very low, we applied the relative risk and odds ratio instead of ordinary method such as t-test to study the characteristics from the 1997 survey data. In order to allocate samples to stratum, we used the compromise of Neyman allocation which is the average of three Neyman allocations. And also, we derive estimators and variance estimators of the estimators.

Velocity Measurement of Fast Moving Object for Traffic Information Acquisition (트래픽 정보 취득을 위한 고속이동물체 속도 측정)

  • Lee Jooshin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.11C
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    • pp.1527-1540
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    • 2004
  • In this paper, velocity measurement of fast moving object for traffic information acquisition using line sampling of image is proposed. Velocity measurement for traffic information acquisition of moving object is that the first sample line and second sample line on the road is set, then car is detected by using difference image method between time-variance hue data of image when car is passing two sample lines and hue data of the reference image, and velocity of the car is measured by using frame number of video which is occupied by two sample lines. Identification of the car is performed by hue of the detected car between the first sample line and second sample line, respectively To examine the propriety of the proposed algorithm, identification and velocity measurement for driving car is evaluated. The evaluated results is that it is identified by hue data of car passing two sample lines, and the velocity measurement for driving car is less than 3% comparing with X-band speed gun.

The Variation of Nutural Population of Pinus densiflora S. et Z. in Korea -Change of variance due to number of family as sample size to affirm the population and family variations- (소나무 천연집단(天然集團)의 변이(變異)에 관(關)한 연구(硏究)(IV) -집단간(集團間) 및 가계간분산(家系間分散) 추정(推定)에 영향하는 가계수(家系數)에 대하여-)

  • Yim, Kyong Bin;Kwon, Ki Won;Lee, Kyong Jae
    • Journal of Korean Society of Forest Science
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    • v.35 no.1
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    • pp.39-46
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    • 1977
  • In the analysis of variance between population and between individual trees (families), the fluctuation of values of variances due to sample size, (number of family) was analysed by two different designs, i.e. 2-level nested design with equal sample size and randomized complete block design. The variables were seedling heights and root calipers of 1-0 and 1-1 seedlings of Pinus densiflora S. et Z. The details of three natural stands and their progeny characters were presented in previous reports. 1. In nested design analysis. increase of sample size resulted the decrease of F-values among families in general, however, the F-values among populations showen the increasing tendency. The smaller the sample size, the larger the F-values fluctuation was resulted in general. At the point of beyond sample size 10, however, the fluctuation become to be stabilized. The F-value fluctuation seemed to be more in the case of analysis with random sampling method than with sequentially accumulated sampling method. And also such a tendency was more obvious in smaller sample size than in large one. 2. In R.C.B.D. analysis, the sample size to affirm the family variation was smaller than that for population variations.

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Evaluation of Sensory Quality of Spices Treated with Ethylene Oxide and Ionizing Radiation (Ethylene Oxide 처리(處理)와 방사선조사(放射線照射) 살균(殺菌) 향신료(香辛料)의 관능적(官能的) 품질평가(品質評價))

  • Byun, Myung-Woo;Kwon, Joong-Ho;Lee, Jae-Won;Cho, Han-Ok
    • Korean Journal of Food Science and Technology
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    • v.18 no.6
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    • pp.427-430
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    • 1986
  • Ionizing irradiation and E.O were used for sterilization of 5 different types of spices and mixed spices, and then each treated sample was evaluated using rank-order test to compare the sensory quality of the E.O fumigated sample to that of the irradiated sample. Preference of tested samples was in the descending order of control, the irradiated and the fumigated samples. According to the results of analysis of variance. 5 spices were significantly different at the 1% (P<0.01) or 5% (P<0.05), while mixed spices showed no significance. The results of Duncan's multiple range test showed that there was no significance difference between control and the irradiated sample, while the E.O fumigated sample was significantly different from control and irradiated samples. In conclusion, no adverse effects was found in quality of spices by ionizing radiation for sterilization, but the E.O fumigated sample showed deterioration of quality. The results were corresponded with the changes in major physicochemical components of each sample.

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Sample Size Determination of Univariate and Bivariate Ordinal Outcomes by Nonparametric Wilcoxon Tests (단변량 및 이변량 순위변수의 비모수적 윌콕슨 검정법에 의한 표본수 결정방법)

  • Park, Hae-Gang;Song, Hae-Hiang
    • The Korean Journal of Applied Statistics
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    • v.22 no.6
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    • pp.1249-1263
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    • 2009
  • The power function in sample size determination has to be characterized by an appropriate statistical test for the hypothesis of interest. Nonparametric tests are suitable in the analysis of ordinal data or frequency data with ordered categories which appear frequently in the biomedical research literature. In this paper, we study sample size calculation methods for the Wilcoxon-Mann-Whitney test for one- and two-dimensional ordinal outcomes. While the sample size formula for the univariate outcome which is based on the variances of the test statistic under both null and alternative hypothesis perform well, this formula requires additional information on probability estimates that appear in the variance of the test statistic under alternative hypothesis, and the values of these probabilities are generally unknown. We study the advantages and disadvantages of different sample size formulas with simulations. Sample sizes are calculated for the two-dimensional ordinal outcomes of efficacy and safety, for which bivariate Wilcoxon-Mann-Whitney test is appropriate than the multivariate parametric test.

Test of the Health Promotion Model (건강증진모델의 검증을 위한 일연구)

  • Lim Nam Young
    • Journal of Korean Public Health Nursing
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    • v.4 no.2
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    • pp.25-34
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    • 1990
  • The Purpose of this study were 1) to find out the characteristics of health promoting Ii festyles of the study samples, 2) to determine the relationships of physical health and mental health, 3) to determine the relationships of health promoting lifestyles and health status. The health promotion model was tested with a volunteer sample of 141 female students in a university in Seoul. The health promoting lifestyle was measured by the scales developed by Walker and Pender(1987). Health status was measured by Cornell medical Index. Pearson's product moment correlations and stepwise multiple regression technique were used to analyze the data. The results are summarized as follows; 1. The items with the highest frequency of the subscales of health promoting lifestyle were 'look forward to the future' $(133,\;95.0\%)$ in self actualization, 'Enjoy being touched and touching people close to me' $(122,\; 87.14\%)$ in relationships with others. The strongest correlation was between general competence In self care and nutritional practice(r=5388, P<. 0001). 2. Fatigability, frequency of illness, miscellaneous diseases, habit, mood and feeling patterns were predictive of mental health. 3. Total health promoting lifestyles explained $14\%$ of the variance for health status. Relationships with others explained $20.9\%$ of the variance for health status. In conclusion, because the most variance explained was $420.9\%$, there must be other variables not accounted for by the model. that influence health promoting behaviors. Psychological factors accounted for more variance than other factors. Intervention studies focused on psychological factors as a means of altering behaviors have great potential for the design of interventions to increase health promoting behaviors. Further testing of the model with this population should be done.

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Emotional Intelligence, Academic Motivation, and Achievement among Health Science Students in Saudi Arabia: A Self-Deterministic Approach

  • Mahrous, Rasha Mohammed;Bugis, Bussma Ahmed;Sayed, Samiha Hamdi
    • Journal of Korean Academy of Nursing
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    • v.53 no.6
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    • pp.571-583
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    • 2023
  • Purpose: This study used a self-deterministic approach to explore the relationship between emotional intelligence (EI), academic motivation (AM), and achievement among health science students. Methods: A descriptive cross-sectional study was conducted in three cities of Saudi Arabia (Dammam, Riyadh, and Jeddah). A convenience sample of 450 students was incorporated using the multistage cluster sampling technique. The online survey contained three sections: students' basic data and academic achievement level, the modified Schutte self-report inventory, and the Academic Motivation Scale lowercase. Results: This study revealed moderate overall scores for EI (57.1%), AM (55.6%), and grade point average (GPA) (57.6%). The overall EI score, its domains, and GPA had significant positive correlations with overall AM and intrinsic and extrinsic motivation (p < .01). Amotivation had an insignificant correlation with GPA (p < .05), but it was negatively correlated with EI and its domains (p < .01). Multiple regression analysis proved that EI domains predicted 5.0% of GPA variance; emotions appraisal and expression (β = .02, p = .024), regulation (β = .11, p = .032), and utilization (β = .24, p < .01). EI domains also predicted 26.0% of AM variance; emotions appraisal and expression (β = .11, p = .04), regulation (β = .33, p < .01), and utilization (β = .23, p < .01). Moreover, AM predicted 4.0% of the variance in GPA; intrinsic (β = .25, p = .004) and extrinsic (β = .11, p = .022) motivation. AM also predicted 25.0% of the variance in EI: intrinsic (β = .34, p < .01) and extrinsic motivation (β = .26, p = .026). Conclusion: EI and AM have a bidirectional influence on each other, significantly shaping the GPA of health sciences students in Saudi Arabia, where intrinsic motivation has a predominant role. Thus, promoting students' AM and EI is recommended to foster their academic achievement.

On Detecting the Best Treatment

  • Kim, Woo-Chul
    • Journal of the Korean Statistical Society
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    • v.17 no.2
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    • pp.81-92
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    • 1988
  • We observe independent random variable $Y_i \sim N(\theta_i,1), i=1,2,\cdots,k$, and we are interested in detecting the treatment with the largest $\theta_i$. We consider a procedure which infers $\theta_{(k)} \geq max\theta_i (i\neq(k))$ whenever $Y_{(k)} \geq maxY_i+C (i\neq(k))$. The maximum probability of a false inference is found, and it is shown that the inference can be made with the two-sample one-sided critical value for the usual error levels. The result also holds in the case of common unknown variance.

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Optimum Design of Accelerated Degradation Tests for Lognormal Distribution

  • Lee, Nak-Young
    • Journal of Korean Society for Quality Management
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    • v.23 no.1
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    • pp.29-40
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    • 1995
  • This paper considers the problem of optimally designing accelerated degradation tests in which the performance value of a specimen is measured only at one of three test conditions for a given exposure time. For the product having lognormally distributed performance, the optimum plan-low stress level and sample proportion allocated to each test condition - is obtained, which minimize the asymptotic variance of maximum likelihood estimator of a stated quantile at design stress. An illustrative example for the optimum plan is given.

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