• Journal of the Korean Statistical Society
• /
• v.7 no.1
• /
• pp.3-10
• /
• 1978

Let $X_i,...,X_n$ be a random sample from a distribution with cumulants $K_1, K_2,...$. The statistic $t = \frac{\sqrt{x}(\bar{X}-K_1)}{S}$ has the well-known 'student' distribution with $\nu = n-1$ degrees of freedom if the $X_i$ are normally distributed (i.e., $K_i = 0$ for $i \geq 3$). An Edgeworth series expansion for the distribution of t when the $X_i$ are not normally distributed is obtained. The form of this expansion is Prob $(t

• Journal of the Korean Institute of Intelligent Systems
• /
• v.21 no.6
• /
• pp.786-791
• /
• 2011

An optimal feature selection and extraction procedure is an important task that significantly affects the success of brain activity analysis in brain-computer interface (BCI) research area. In this paper, a novel method for extracting the optimal feature from electroencephalogram (EEG) signal is proposed. At first, a student's-t-statistic method is used to normalize and to minimize statistical error between EEG measurements. And, 2D time-frequency data set from the raw EEG signal was extracted using discrete wavelet transform (DWT) as a raw feature, standard deviations and mean of 2D time-frequency matrix were extracted as a optimal EEG feature vector along with other basis feature of sub-band signals. In the experiment, data set 1 of BCI competition IV are used and classification using SVM to prove strength of our new method.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.14 no.4
• /
• pp.429-436
• /
• 2007

Purpose: This study was conducted to identify the knowledge, attitude and self-confidence of student nurses regarding control of nosocomial infections and to provide data for preparation of an efficient policy and education program regarding nosocomial infections. Method: A descriptive survey design was utilized, and, using a questionnaire, which included 15 items for knowledge, 81 items for attitude, 81 items for self-confidence, data were collected from 520 student nurses. Descriptive statistic, t-test, one-way ANOVA and Pearson's correlation coefficients, and Stepwise multiple regression analysis were used with SPSS win 12.0 to analyze the data. Results: The mean score for knowledge was 0.63, for attitude, 4.38 and for self-confidence, 3.50. There was a significant positive correlation between knowledge, attitude and self-confidence in control of nosocomial infections. Attitude, practical attitude, and education were significant factors affecting self-confidence regarding nosocomial infection control. Conclusion: These research findings should be useful in promoting continuous and repeated educational programs on nosocomial infection for student nurses.

• Perspectives in Nursing Science
• /
• v.10 no.2
• /
• pp.97-110
• /
• 2013

Purpose: This study sought to identify how initiating breastfeeding soon after birth affected breastfeeding practice. Methods: The subjects were mothers and newborns in Seoul's S. University Hospital maternity unit who elected to breastfeed. They were divided into an experimental group, which practiced an "early latching-on program" (latching-on within 30 minutes after birth), and a control group, which did not. Both groups' daily frequencies of breastfeeding and supplementary-glucose or bottle feeding were recorded. Results: The correlation between socio-demographic and medical characteristics and the breastfeeding rate was examined; 3 variables showed statistical significance: neonatal health anomaly, Apgar score after 1 minute, and Apgar score after 5 minutes. The difference in breastfeeding rates between the two groups was clear: the experimental group's rate was 1.93, while the control group's was 3.76 (t-statistic difference: 14.865), with the experimental group's rate during hospitalization being twice that of the control group (73.3% and 32.6%, respectively). Multiple regression analysis assessing the influence of the latching-on program yielded a t-statistic of -4.735 and a p-value of .000, indicating statistical significance. Conclusion: An early latching-on program's positive effect on the breastfeeding practice of mother's of newborns was demonstrated. Therefore, an early latching-on program could be a practical and effective nursing intervention for after mothers give birth.

• Journal of the Korean Statistical Society
• /
• v.5 no.2
• /
• pp.91-100
• /
• 1976

The use of the statistic $t = \sqrt{n} (x-\mu)/S$, where $\bar{X) = \sum X_i/n, \mu = E(X_i), S^2 = \sum(X_i-\bar{X})^2/(n-1)$ in statistical inference is usually done under the assumption of normality of the population. If the population is not normally distributed the tabulated values of student t are no longer valid. The moments of t are obtained as a power series in $1/\sqar{n}$ whose coefficients are functions of the cumulants of X. The cumulants are obtained from the moments in the usual manner. The first eight cumulants of t are given up to terms of order $1/n^3$. The first eight cumulants of t are given up to terms of order $1/n^3$. These results extend those of Geary who gave the first six cumulants of t to order $1/n^2$.

• Journal of Korean Public Health Nursing
• /
• v.18 no.1
• /
• pp.143-153
• /
• 2004

The study tried to develop a parent-involvement sex education program and find out its effects for more effective sex education methods for high graders of a primary school. The subjects were recruited from 5 classes of 6th graders in Y Primary School in N city, Kyeonggido province, South Korea. Data collection was done from October 4, 2003 to November 7. The experimental group consisted of 43 students from 3 classes with the help from class teachers and parents' involvement in the program. The control group consisted of 43 students randomly sampled by computer from the other two classes. For the experimental methods, the experimental group was given a parent-involvement sex education program as well as a student sex education program: the control group only received the student sex education program. The results were analyzed according to frequency, percentage, $x^2$-test, fisher's exact test and t-test using SAS program. As a result of the homogeneity test, both the groups proved to be the same (t=-0.29 p=0.77, t=0.49 p=0.62) in preliminary sex-attitude and sex-related communication frequency score. But the two group showed meaningful differences (t=2.52 p=0.01, t=2.04, p=0.04) in preliminary sex-knowledge and sex-related communication quality score. After the sex education programs, the two groups didn't show meaningful statistic differences(t=-0.42 p=0.68, t=1.57 p=0.12) in preliminary sex-knowledge and sex-related communication quality score. But the experimental group was statistically more meaningful (t=2.16 p=0.03, t=4.86 p<0.0001) in the difference of sex attitude and sex-related communication frequency than the control. The parent-involvement sex education program developed in this study was more effective for improving their sex attitude and for increasing the frequency of their sex-related communication with parents than the existing student program. Therefore, for sex education, it's necessary to develop and spread various programs where parents can be involved.

• Science of Emotion and Sensibility
• /
• v.20 no.2
• /
• pp.149-160
• /
• 2017

In hypothesis testing, the interpretation of a statistic obtained from the data analysis relies on a probabilistic distribution of the statistic constructed according to several statistical theories. For instance, the statistical significance of a mean difference between experimental conditions is determined according to a probabilistic distribution of the mean differences (e.g., Student's t) constructed under several theoretical assumptions for population characteristics. The present study explored the logic and advantages of random-resampling approach for analyzing event-related potentials (ERPs) where a hypothesis is tested according to the distribution of empirical statistics that is constructed based on randomly resampled dataset of real measures rather than a theoretical distribution of the statistics. To motivate ERP researchers' understanding of the random-resampling approach, the present study further introduced a specific example of data analyses where a random-permutation procedure was applied according to the random-resampling principle, as well as discussing several cautions ahead of its practical application to ERP data analyses.

• Interdisciplinary Bio Central
• /
• v.2 no.2
• /
• pp.4.1-4.6
• /
• 2010

The most common type of microarray experiment has a simple design using microarray data obtained from two different groups or conditions. A typical method to identify differentially expressed genes (DEGs) between two conditions is the conventional Student's t-test. The t-test is based on the simple estimation of the population variance for a gene using the sample variance of its expression levels. Although empirical Bayes approach improves on the t-statistic by not giving a high rank to genes only because they have a small sample variance, the basic assumption for this is same as the ordinary t-test which is the equality of variances across experimental groups. The t-test and empirical Bayes approach suffer from low statistical power because of the assumption of normal and unimodal distributions for the microarray data analysis. We propose a method to address these problems that is robust to outliers or skewed data, while maintaining the advantages of the classical t-test or modified t-statistics. The resulting data transformation to fit the normality assumption increases the statistical power for identifying DEGs using these statistics.

• The Journal of the Korea Contents Association
• /
• v.15 no.10
• /
• pp.316-326
• /
• 2015

The present study aims to investigate the association between knowledge, attitude, and practice of blood donating in an effort to increase the participation rate of blood donation among university students. Data was obtained among 272 in theirs 20s health sciences students in two university of South Korea through self-reported questionnaires including Knowledge, attitude, and behavioral practice regarding blood donation during 8st December 2014 to 12st December 2014. Pearson correlation test, student's t-test or descriptive statistics were performed for the data analysis. The results were as follows: 1) There was positive significant relationship between Attitude and behavioral practice towards blood donation(P <.05). 2) There was significant difference in the knowledge(P<.01) and attitude(P<.05) regarding blood donation according to public health vs non-public health. 3) The participants with previous blood donation experiences showed a higher participation rate than those without such an experience(P<.01). It is important not only to improve the university student's attitude towards blood donation through media advertising but also to reinforce the compensation offered to donors.

• Journal of the Korean Statistical Society
• /
• v.32 no.4
• /
• pp.425-448
• /
• 2003

Meta-analysis refers to quantitative methods for combining results from independent studies in order to draw overall conclusions. We consider hierarchical models including selection models under a skewed heavy tailed error distribution proposed originally by Chen et al. (1999) and Branco and Dey (2001). These rich classes of models combine the information of independent studies, allowing investigation of variability both between and within studies, and incorporate weight function. Here, the testing for the skewness parameter is discussed. The score test statistic for such a test can be shown to be expressed as the posterior expectations. Also, we consider the detail computational scheme under skewed normal and skewed Student-t distribution using MCMC method. Finally, we introduce one example from Johnson (1993)'s real data and apply our proposed methodology. We investigate sensitivity of our results under different skewed errors and under different prior distributions.