• Title/Summary/Keyword: Chi-bar-square

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Testing for Failure Rate Ordering between Survival Distributions

  • Park, Chul-Gyu
    • Journal of the Korean Statistical Society
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    • v.23 no.2
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    • pp.349-365
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    • 1994
  • We develop in this paper the likelihood ratio test (LRT) for testing $H_1 : F_1 \preceq F_2$ against $H_2 - H_1$ where $H_2$ imposes no restriction on $F_1$ and $F_2$ and '$\preceq$' means failure rate ordering. Both one and two-sample problems will be considered. In the one-sample case, one of the two distributions is known, while we assume in the other case both are unknown. We derive the asymptotic null distribution of the LRT statistic which will be of chi-bar-square type. The main issue here is to determine the least favorable distribution which is stochastically largest within the class of null distributions.

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Inference for Order Restrictions on Odds in 2 * k Contingency Tables

  • Oh, Myong-Sik
    • Journal of the Korean Statistical Society
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    • v.25 no.3
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    • pp.381-391
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    • 1996
  • In the analysis of contingency table with ordered categories, the relationship between odds for adjacent categories has received con-siderable interest. We consider likelihood ratio tests of independence against an order restriction on odds in 2 $\times$ k contingency tables.

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An Attempt to Model Distributions of Machined Component Dimensions in Production

  • Cogun, Can;Kilinc, Biinyamin
    • Journal of Mechanical Science and Technology
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    • v.16 no.1
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    • pp.60-74
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    • 2002
  • In this study, normal, log-normal, triangular, uniform. Weibull, Erlang and unit beta probability density functions are tried to represent the behaviour of frequency distributions of workpiece dimensions collected from various manufacturing firms. Among the distribution functions, the unit beta distribution function is found to be the best fit using the chi-square test of fit. An attempt is made for the adoption of the unit beta model to x-bar charts of quality control in manufacturing. In this direction, upper and lower control limits (UCL and LCL) of x-bar control charts of dimension measurements are estimated for the beta model, and the observed differences between the beta and normal model control limits are discussed for the measurement sets.

Statistical Inference Concerning Local Dependence between Two Multinomial Populations

  • Oh, Myong-Sik
    • Journal of the Korean Data and Information Science Society
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    • v.14 no.2
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    • pp.413-428
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    • 2003
  • If a restriction is imposed only to a (proper) subset of parameters of interest, we call it a local restriction. Statistical inference under a local restriction in multinomial setting is studied. The maximum likelihood estimation under a local restriction and likelihood ratio tests for and against a local restriction are discussed. A real data is analyzed for illustrative purpose.

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Test of Local Restriction on a Multinomial Parameter

  • Oh, Myongsik
    • Communications for Statistical Applications and Methods
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    • v.10 no.2
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    • pp.525-534
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    • 2003
  • If a restriction is imposed only to a (proper) subset of parameters of interest, we call it a local restriction. Statistical inference under a local restriction in multinomial setting is studied. The maximum likelihood estimation under a local restriction and likelihood ratio tests for and against a local restriction are discussed. A real data is analyzed for illustrative purpose.

Comparing More than Two Agreement Measures Using Marginal Association

  • Oh, Myong-Sik
    • Communications for Statistical Applications and Methods
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    • v.16 no.6
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    • pp.1023-1029
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    • 2009
  • Oh (2009) has proposed a likelihood ratio test for comparing two agreements for dependent observations based on the concept of marginal homogeneity and marginal stochastic ordering. In this paper we consider the comparison of more than two agreement measures. Simple ordering and simple tree ordering among agreement measures are investigated. Some test procedures, including likelihood ratio test, are discussed.

Statistical Inference Concerning Peakedness Ordering between Two Symmetric Distributions

  • Oh, Myong-Sik
    • Journal of the Korean Data and Information Science Society
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    • v.15 no.1
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    • pp.201-210
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    • 2004
  • The peakedness ordering is closely related to dispersive ordering. In this paper we consider the statistical inference concerning peakedness ordering between two arbitrary symmetric distributions. Nonparametric maximum likelihood estimates of two distribution functions under symmetry and peakedness ordering are given. The likelihood ratio test for equality of two symmetric discrete distributions in the sense of peakedness ordering is studied.

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Tests For and Against a Positive Dependence Restriction in Two-Way Ordered Contingency Tables

  • Oh, Myongsik
    • Journal of the Korean Statistical Society
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    • v.27 no.2
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    • pp.205-220
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    • 1998
  • Dependence concepts for ordered two-way contingency tables have been of considerable interest. We consider a dependence concept which is less restrictive than likelihood ratio dependence and more restrictive than regression dependence. Maximum likelihood estimation of cell probability under this dependence restriction is studied. The likelihood ratio statistics for and against this dependence are proposed and their large sample distributions are derived. A real data is analyzed to illustrate the estimation and testing procedures.

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Factors Affecting Experience of Decayed and Decalcified Teeth of Infants Aged 18-24 Months (18-24개월 시기에 경험하는 우식치와 탈회치에 영향을 미치는 요인)

  • Lim, Soon Ryun;Woo, Hee-Sun
    • Journal of dental hygiene science
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    • v.11 no.3
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    • pp.205-211
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    • 2011
  • The present study seeks to find the effect of oral health status that parents recognized, oral health habit and food intake on existence of decalcified teeth and decayed teeth. Participants were 293 infants aged 18-24 months who visited C dental clinic in Kyungki province between January and December 2010. Questionnaires and oral exam results were used and statistically analyzed by the SPSS program. Fisher's Exact and chi-square test were used to analyze the data. The 18-20 month-old age group had the highest rate of decalcified teeth with 36.4% while the 23-24 month-old age group had the highest rate of decayed teeth with 37.0%. Bottle feeding showed correlation with decalcified teeth, and decayed teeth. Parents were able to recognize decayed teeth and decalcified teeth. Group 2 food(soda/soft drinks/sugared fruit juice) was related to decalcified teeth and decayed teeth(p<.001). Group 4 food (cake/cookies/doughnut/dried fruit/banana) and group 5food(caramel/candy/chocolate bar) were both related to decalcified teeth(p<.001). As the result of dental examination, dental treatment was highly needed for the 21-22 month-old age group(89.3%), and preventive treatment and plaque control were highly needed for the 18-20 month-old age group(94.5%). The results concluded that 18-24 months was the critical period for children's oral health, therefore organized oral health education for parents is necessary.

The Effect of Dance Therapy on Physical and Psychological Characteristics in The Elderly (무용요법이 노인의 신체적.심리적 특성에 미치는 효과)

  • 이영란
    • Journal of Korean Academy of Nursing
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    • v.29 no.2
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    • pp.429-444
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    • 1999
  • This study was performed to explore the effects of a dance therapy on physical and psychological characteristics in the elderly. The design of this study was a non-equivalent pre-post test experiment. The subjects consisted of elderly persons living in a facility located in Suweon and Bucheon. Fifty eight subjects, aged between 65 and 93 years who had normal cognition, sensory function, balance, and resting blood pressure. They underwent tests of balance, flexibility, muscle strength, depression, and anxiety as baseline data before dance therapy, and at 6th week and at the end of the 12nd week after following dance therapy. Twenty seven elderly persons were assigned to the experimental group and participated with the dance therapy between April and July, 1998. The dance therapy was developed by the author with the help of a dance therapist and a physiatrist. This therapy was based on the Marian Chace's dance therapy and Korean traditional dance with music. The dance therapy consists of 50 minutes session, 3 times a week for 12 weeks. One session was consisted of warming-up, expression, catharsis, sharing, and closing stage. The intensity of the dance therapy was at the 40 % of age-adjusted maximum heart rates. Data were analysed with mead standard deviation, Chi-square test, unpaired t-test, repeated measures ANOVA, and Bonferroni multiple regression using SAS program. 1. The results related to the physical characteristics were as follows : 1) The balance (standing on one leg, walking on the balancing bar), flexibility and muscle strength (knee extensor, knee flexor, ankle plantarflexor and dorsiflexor) of the experimental subjects significantly increased over time mere than that of the control subjects. 2) The experimental group had significantly higher score for balance, flexibility, muscle strength of knee extensor, and knee flexor than the control group at the 12nd week after dance therapy. 3) The experimental group had significantly higher score for muscle strength of ankle dorsiflexor and plantarflexor than the control group at the 6th week and the 12nd week after dance therapy. 2. The results related to psychological characteristics were as follows : 1) Scores of Geriatric Depression Scale, Hamilton Depression Rating Scale, and Zung's Self-rating Anxiety Scale of the experimental group were significantly decreased over time more than that of the control group. 2) The experimental group had significantly lower score for depression than the control group at the 12nd week after dance therapy. 3) The experimental group had significantly lower score for anxiety than the control group at the 6th week and the 12nd week after dance therapy. The findings showed that the dance therapy could be effective in improving the balances, flexibility, and muscle strength of lower limb, and effective in decreasing the depression and anxiety of the elderly. Additional merits of the dance therapy would be inexpensiveness, easy accessibility, and increasing interpersonal relationship. It can be suggested that the dance therapy is effective in the health promotion of the elderly.

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