• Title, Summary, Keyword: sample number

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Reproducibility and Sample Size in High-Dimensional Data (고차원 자료의 재현성과 표본 수)

  • Seo, Won-Seok;Choi, Jee-A;Jeong, Hyeong-Chul;Cho, Hyung-Jun
    • The Korean Journal of Applied Statistics
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    • v.23 no.6
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    • pp.1067-1080
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    • 2010
  • A number of methods have been developed to determine sample sizes in clinical trial, and most clinical trial organizations determine sample sizes based on the methods. In contrast, determining sufficient sample sizes needed for experiments using microarray chips is unsatisfactory and not widely in use. In this paper, our objective is to provide a guideline in determining sample sizes, utilizing reproducibility of real microarray data. In the reproducibility comparison, five methods for discovering differential expression are used: Fold change, Two-sample t-test, Wilcoxon rank-sum test, SAM, and LPE. In order to standardize gene expression values, both MAS5 and RMA methods are considered. According to the number of repetitions, the upper 20 and 100 gene accordances are also compared. In determining sample sizes, more realistic information can be added to the existing method because of our proposed approach.

Analysis of Accident Factors at Arterial Roads Using Tobit Model (Tobit 모형을 이용한 간선도로 사고 요인 분석)

  • Kim, Kyung Hwan;Park, Byung Ho
    • International Journal of Highway Engineering
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    • v.15 no.2
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    • pp.131-138
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    • 2013
  • PURPOSES : The intents of the study are to identify the accident factors and to demonstrate the potentials of tobit model as a tool to study the number of accidents on arterial roads segments. METHODS : This paper uses a tobit regression as a methodology to analyze the factors affecting the number of accidents. In pursuing the above goal, this study gives particular attentions to analyzing the data of 2,446 accidents (1,610 in major arterial roads and 836 in minor arterial roads) occurred on arterial roads in 2007 to 2010. RESULTS : First, 3 accident models which were classified by total arterial roads, major arterial roads and minor arterial roads, and were all statistically significant were developed. Second, the exclusive right-turn lane as common variable, and the number of accident, traffic volume, number of lanes, link length, rate of median, number of entrances, number of pedestrian crossings, number of curves, number of bus stops and exclusive left-turn as specific variables of the models were selected. Finally, the paired sample t-test could not be rejected the null hypotheses of three types of models. CONCLUSIONS : Using data from vehicle accidents on arterial roads, the estimation results show that many factors related to roadway geometrics and traffic characteristics significantly affect to the number of accidents.

A Study on the Effectiveness of Averaged MUSIC Using Limited Number of Sensors (제한된 수의 Sensor를 이용한 Averaged MUSIC의 효율성에 관한 연구)

  • 김영집
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.206-209
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    • 1993
  • The main purpose of this paper is to verify the effectiveness of a high resolution direction finding method, so called the‘averaged MUSIC’. This method uses a new sample array covariance matrix that consists of diagonal components obtained by taking averages of the diagonal component values of the sample covariance matrix for the MUSIC. The paper shows that the proposed method performs higher resolved direction-of-arrival estimation and better resolution probability than the MUSIC in such cases as low signal-to-noise ratio, when the number of sensors used is finite, based on the statistical analysis.

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EFFICIENT REPLICATION VARIANCE ESTIMATION FOR TWO-PHASE SAMPLING

  • Kim, Jae-Kwang;Sitter, Randy
    • Proceedings of the Korean Statistical Society Conference
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    • pp.327-332
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    • 2002
  • Variance estimation for the regression estimator for a two-phase sample is investigated. A replication variance estimator with number of replicates equal to or slightly larger than the size of the second-phase sample is developed. In these cases, the proposed method is asymptotically equivalent to the full jackknife, but uses smaller number of replications.

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Multi-Level Skip-Lot Sampling Plan-Average Fraction Inspected Properties

  • In-Suk Lee;Gyo-Young Cho;Hae-Rim Kim
    • Communications for Statistical Applications and Methods
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    • v.3 no.2
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    • pp.151-159
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    • 1996
  • The general formulas of average fraction inspected, average sample number and average outgoing quality in n-level skip-lot sampling plan are derived. Average sample number and average outgoing quality of a reference plan, three-level, five-level and ten-level skip-lot sampling plans are compared.

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A Heuristic Approach for Approximating the ARL of the CUSUM Chart

  • Kim, Byung-Chun;Park, Chang-Soon;Park, Young-Hee;Lee, Jae-Heon
    • Journal of the Korean Statistical Society
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    • v.23 no.1
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    • pp.89-102
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    • 1994
  • A new method for approximating the average run length (ARL) of cumulative sum (CUSUM) chart is proposed. This method uses the conditional expectation for the test statistic before the stopping time and its asymptotic conditional density function. The values obtained by this method are compared with some other methods in normal and exponential case.

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Sample Preparation and Nucleic Acid-based Technologies for the Detection of Foodborne Pathogens (식중독균의 검출을 위한 시료전처리 및 핵산기반의 분석기술)

  • Lim, Min-Cheol;Kim, Young-Rok
    • Food Engineering Progress
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    • v.21 no.3
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    • pp.191-200
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    • 2017
  • There have been great efforts to develop a rapid and sensitive detection method to monitor the presence of pathogenic bacteria in food. While a number of methods have been reported for bacterial detection with a detection limit to a single digit, most of them are suitable only for the bacteria in pure culture or buffered solution. On the other hand, foods are composed of highly complicated matrices containing carbohydrate, fat, protein, fibers, and many other components whose composition varies from one food to the other. Furthermore, many components in food interfere with the downstream detection process, which significantly affect the sensitivity and selectivity of the detection. Therefore, isolating and concentrating the target pathogenic bacteria from food matrices are of importance to enhance the detection power of the system. The present review provides an introduction to the representative sample preparation strategies to isolate target pathogenic bacteria from food sample. We further describe the nucleic acid-based detection methods, such as PCR, real-time PCR, NASBA, RCA, LCR, and LAMP. Nucleic acid-based methods are by far the most sensitive and effective for the detection of a low number of target pathogens whose performance is greatly improved by combining with the sample preparation methods.

Evaluation of a Sample-Pooling Technique in Estimating Bioavailability of a Compound for High-Throughput Lead Optimazation (혈장 시료 풀링을 통한 신약 후보물질의 흡수율 고효율 검색기법의 평가)

  • Yi, In-Kyong;Kuh, Hyo-Jeong;Chung, Suk-Jae;Lee, Min-Haw;Shim, Chang-Koo
    • Journal of Pharmaceutical Investigation
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    • v.30 no.3
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    • pp.191-199
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    • 2000
  • Genomics is providing targets faster than we can validate them and combinatorial chemistry is providing new chemical entities faster than we can screen them. Historically, the drug discovery cascade has been established as a sequential process initiated with a potency screening against a selected biological target. In this sequential process, pharmacokinetics was often regarded as a low-throughput activity. Typically, limited pharmacokinetics studies would be conducted prior to acceptance of a compound for safety evaluation and, as a result, compounds often failed to reach a clinical testing due to unfavorable pharmacokinetic characteristics. A new paradigm in drug discovery has emerged in which the entire sample collection is rapidly screened using robotized high-throughput assays at the outset of the program. Higher-throughput pharmacokinetics (HTPK) is being achieved through introduction of new techniques, including automation for sample preparation and new experimental approaches. A number of in vitro and in vivo methods are being developed for the HTPK. In vitro studies, in which many cell lines are used to screen absorption and metabolism, are generally faster than in vivo screening, and, in this sense, in vitro screening is often considered as a real HTPK. Despite the elegance of the in vitro models, however, in vivo screenings are always essential for the final confirmation. Among these in vivo methods, cassette dosing technique, is believed the methods that is applicable in the screening of pharmacokinetics of many compounds at a time. The widespread use of liquid chromatography (LC) interfaced to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) allowed the feasibility of the cassette dosing technique. Another approach to increase the throughput of in vivo screening of pharmacokinetics is to reduce the number of sample analysis. Two common approaches are used for this purpose. First, samples from identical study designs but that contain different drug candidate can be pooled to produce single set of samples, thus, reducing sample to be analyzed. Second, for a single test compound, serial plasma samples can be pooled to produce a single composite sample for analysis. In this review, we validated the issue whether the second method can be applied to practical screening of in vivo pharmacokinetics using data from seven of our previous bioequivalence studies. For a given drug, equally spaced serial plasma samples were pooled to achieve a 'Pooled Concentration' for the drug. An area under the plasma drug concentration-time curve (AUC) was then calculated theoretically using the pooled concentration and the predicted AUC value was statistically compared with the traditionally calculated AUC value. The comparison revealed that the sample pooling method generated reasonably accurate AUC values when compared with those obtained by the traditional approach. It is especially noteworthy that the accuracy was obtained by the analysis of only one sample instead of analyses of a number of samples that necessitates a significant man-power and time. Thus, we propose the sample pooling method as an alternative to in vivo pharmacokinetic approach in the selection potential lead(s) from combinatorial libraries.

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Quality Characteristics of Baked Yugwabandagi with Different Additives (첨가물을 달리한 구운 유과 반대기의 품질 특성)

  • Cha, Kyoung-Ok;Han, Eun-Ju
    • Journal of the East Asian Society of Dietary Life
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    • v.25 no.3
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    • pp.492-501
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    • 2015
  • To improve the shortcomings of baked Yugwa 0.5, 1.0, 1.5 and 2.0% natural ind igestible materials,- (gellan gum, glucomannan and carrageenan) were each treated with glutinous rice-baked Yugwa was processed, and quality imprpvements were deducted. Baked Yugwa with natural additives,- (gellan gum, glucomannan and carrageenan) was compared,- to additional test results with sample 1.5%(w/w) additives,- The one showing the highest preference from the sensory test was the acid number reference group at $2.19{\pm}0.42$, while the sample groups,- with different additives, were lower than the reference group by $1.48{\pm}0.39$ to $1.67{\pm}0.68$. The peroxide number reference group showed the highest preference of $49.34{\pm}0.42$, whereas the sample groups, with different additives, showed lower preferences than the reference group by $36.72{\pm}$0.42 compared to the sample group of glucomannan 1.5% (w/w), $32.45{\pm}0.59$ compared to the sample group of gellan gum 1.5%(w/w), and $28.65{\pm}0.56$ compared to the sample group of carrageenan 1.5% (w/w). According to the preference test targeting employees of Korean cake, manufacturers, there was no significant difference in color and flavor among all groups, whereas the sample group of carrageenan 1.5% (w/w) showed the highest scores in items of taste, texture and overall-preference, and also sample groups of glucomannan 1.5% (w/w) and gellan gum 1.5% (w/w) scored higher than the reference group. Baked Yugwa with 1.5% (w/w) additives of carrageenan, glucomannan and gellan gum have higher marketability by decreasing deterioration caused by oxidation of existing deep fried Yugwa and by improving the solid texture of baked Yugwa.

Adsorption Characteristics of Liquid Chromatography with Preparative Packings (제조용 충전물을 사용한 액체 크로마토그래피의 흡착특성)

  • Choi, Yong Seok;Lee, Chong Ho;Row, Kyung Ho
    • Applied Chemistry for Engineering
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    • v.9 no.3
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    • pp.430-434
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    • 1998
  • Preparative HPLC (High-Performance Liquid Chromatography) is mainly used for separating useful component from biological samples. By reversed-phase HPLC packed with preparative packings ($15{\mu}m$), the adsorption characteristics with sample size were investigated. Sample was 5'-GMP, a flavor enhancer, and the composition of mobile phase was 20mM $KH_2PO_4$ solution:methanol (97:3 vol.%). From the experimental results, the effect of sample size on retention factor was negligible, but the peak was asymmetrical above $1{\mu}g$ of sample. In addition, the increase in sample size deteriorated the number of theoretical plates, and at small concentration, the number of theoretical plates was less because of large peak width. In the experimental condition, the adsorption isotherm of 5'-GMP was relatively well represented by Freundlich equation.

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