• Communications for Statistical Applications and Methods
• /
• v.25 no.5
• /
• pp.545-557
• /
• 2018

The inclusion of covariates in the model often affects not only the estimates of meaningful variables of interest but also its statistical significance. Such gap between statistical and subject-matter significance is a critical issue in huge sample studies. A popular huge sample study, the sample cohort data from Korean National Health Insurance Service, showed such gap of significance in the inference for the effect of obesity on cause of mortality, requiring careful consideration. In this regard, this paper proposes a sample size calibration method based on a Monte Carlo t (or z)-test approach without Monte Carlo simulation, and also proposes a test procedure for subject-matter significance using this calibration method in order to complement the deflated p-value in the huge sample size. Our calibration method shows no subject-matter significance of the obesity paradox regardless of race, sex, and age groups, unlike traditional statistical suggestions based on p-values.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.10 no.1
• /
• pp.117-128
• /
• 2004

I have processed all the data by using SPSS PC+. And my research process was investigated for 34 students on the Forward Bending Test, Foot Printer Test, Feedoscope Test, X-ray Test and so on. The object of this thesis is to study the correlation between spine deformity and foot abnormality in a theoretical and empirical method. The main results of this study were as follows: 1. There was statistical significance on the correlation between foot length and spine length. 2. Spinal curve is the smallest on the pes plannus group and the biggest on the pes cavus group without statistical significance. 3. Left lumbar curve is the smallest, and right thoracic spine curve is the biggest on the left foot pattern group with statistical significance. 4. On the foot weight bearing groups, there was statistical significance both of between left and right foot groups. 5. There was no statistical significance on the t-test analysis between left and right foot area according to spinal curve typology. But there was tendency that thoracic spine curve is bigger in the same side of the foot area and lumbar spine curve is bigger in the opposite side of foot area.

• Journal of Korean Physical Therapy Science
• /
• v.10 no.1
• /
• pp.109-121
• /
• 2003

The purpose of this study was to test the difference of sitting balance control between a normal group and a group of patients with low back pain when their eyes were opened or closed. The 30 subjects of the control group had been chosen from healthy individuals who fit into the pre-designed criteria, and the 30 subjects of the experimental group were composed of the patients with LBP who had their treatment from S hospital from september 1, 2002, to October 30, 2002, and the subjects were measured by static balance test by using a balance performance monitor(BPM). Static balance test was done twice for each subject with his or her eyes opened and closed. Collected data were statistically analyzed by SPSS/PC using unpaired T-Test, Pained T-Test and multiple regression. The results were as follows: 1. In static balance test, normal group did not show statistical significance in sway angle(Anterior, Posterior, left and Right), sway path, sway area and maximal sway velocity, but showed statistical significance in mean balance with eyes opened and eyes dosed(P<.05) 2. In static balance test, LBP group did not show statistical significance in sway angle(Anterior, Posterior, left and Right), mean balance, sway path, sway area and maximal sway velocity with eyes opened and eyes dosed 3. With eyes opened, the comparison between the normal group and the LBP group showed statistical significance in sway angle(Anterior, Posterior, left and Right), mean valance, sway path, sway area and maximal sway velocity(p<.05). With eyes closed, normal group and LBP group did not show statistical significance in sway angle(Anterior and Right), sway area, but showed statistical significance in sway angle(Posterior and Left), mean balance, sway path, sway area and maximal sway velocity(p<.05) In conclusion, there was a significant difference in static sitting balance between normal group and LBP patients group. For future studies, I strongly suggest that researches be done on the treatment with LBP by predicting changes of postures and manipulating them.

• Journal of the Korean Statistical Society
• /
• v.5 no.1
• /
• pp.3-18
• /
• 1976

To test simultaneous significance of more than two linear regression coefficients, we can consider multivariate-t tests with critical regions in t-space instead of F-tests where t-values are t-statistics of significance tests of one coefficient. In this paper bivariate-t distributions and bivariate-t tests of two coefficients such as maxmod, minmod, one-tailed maxmod and one-tailed minmod tests are studied. Through the calculation of powers of test, it is learned that in some cases bivariate-t test are more powerful than F-tests.

• Communications for Statistical Applications and Methods
• /
• v.14 no.2
• /
• pp.443-457
• /
• 2007

This paper deals with the problem of testing the existence of change in mean and estimating the change-point using nonparametric bootstrap technique. A test statistic using Gombay and Horvath (1990)'s functional form is applied to derive a test statistic and nonparametric change-point estimator with bootstrapping idea. Achieved significance level of the test is calculated for the proposed test to show the evidence against the null hypothesis. MSE and percentiles of the bootstrap change-point estimators are given to show the distribution of the proposed estimator in simulation.

• The Journal of Korean Physical Therapy
• /
• v.12 no.1
• /
• pp.33-40
• /
• 2000

This study was carried out to compare the relation between vestibular function and balance skills in normal with heating-impaired children. The subjects were 20 normal children (8-10 years) and 20 hearing-impaired children (8-10 years). The SCPNT was used to assess vestibular function, then, functional reach test and backward walking test were usee to compare dynamic balance skills of normal and hearing-impaired children according to existence of visual input. The results were as follows : 1. In SCPNT, normal and hearing-impaired children showed statistical significance in all left-sided and right-sided rotations(p<.01), and the vestibular function responses of healing-impaired children were normal $20\%$, abnormal $45\%$, absent $35\%$. 2, To compare dynamic balance skills between normal and healing-impaired according to eye open and eye close, functional reach test did not show statistical significance in eye open situation(p>.05), but showed statistical significance in eye close situation(p<.05). 3. Backward walking test showed statistical significance in eye open and eye close situation(p<.01).

• Journal of Korean Academy of Nursing
• /
• v.45 no.5
• /
• pp.641-649
• /
• 2015

Purpose: The purpose of this study was to introduce the main concepts of statistical testing and effect size and to provide researchers in nursing science with guidance on how to calculate the effect size for the statistical analysis methods mainly used in nursing. Methods: For t-test, analysis of variance, correlation analysis, regression analysis which are used frequently in nursing research, the generally accepted definitions of the effect size were explained. Results: Some formulae for calculating the effect size are described with several examples in nursing research. Furthermore, the authors present the required minimum sample size for each example utilizing G*Power 3 software that is the most widely used program for calculating sample size. Conclusion: It is noted that statistical significance testing and effect size measurement serve different purposes, and the reliance on only one side may be misleading. Some practical guidelines are recommended for combining statistical significance testing and effect size measure in order to make more balanced decisions in quantitative analyses.

• The Journal of Korean Physical Therapy
• /
• v.13 no.2
• /
• pp.265-272
• /
• 2001

The object of this thesis is to study the correlation between scoliosis and foot in a theoretical and empirical method. My research process was investigated for 34 students on the forward bending test, foot printer test, feedoscope test, X-ray test and so on. The main results of this study were as follows: 1. There was statistical significance on the correlation between foot length and spine length. 2. Scoliosis angle is the smallest on the pes plannus group and the biggest on the pes cavus group without statistical significance. 3. Left lumbar curve is the smallest, and right thoracic spine curve is the biggest on the left foot pattern group with statistical significance. 4. On the foot weightbearing groups, there was statistical significance both of between left and right foot groups. 5. There was no statistical significance on the t-test analysis between left foot area and right foot area according to scoliosis typology.

• Communications for Statistical Applications and Methods
• /
• v.10 no.2
• /
• pp.619-626
• /
• 2003

Given a prior guess for the unknown value of P(Y

• Communications for Statistical Applications and Methods
• /
• v.8 no.1
• /
• pp.219-227
• /
• 2001

Another approach (multi-parameter measurement method) of interlaboratory studies of test methods is presented. When the unrestricted normal likelihood for the fixed latent variable model is unbounded, we propose a me쇙 of restricting the parameter space by formulating realistic alternative hypothesis under which the likelihood is bounded. A simulation study verified the claim of conservatism of level of significance based on assumptions about central chi-square distributed test statistics and on Bonferroni approximations. We showed a randomization approach that furnished empirical significance levels would be better than a Bonferroni adjustment.