共查询到20条相似文献，搜索用时 32 毫秒
1.
Padma Yalamati Madhu Latha Karra Aparna V. Bhongir 《Indian journal of clinical biochemistry : IJCB》2016,31(4):463-467
The total proteins in human urine have been compared by sulfosalicylic acid, sulfosalicylic acid with sodium sulphate and trichloroacetic acid methods with pyrogallol red molybdate method as there are no studies found quantifying imprecision and bias components. Fresh urine of 36 patients was analyzed by four methods. Imprecision and inaccuracy were determined by repeated analysis and method comparison studies using correlation plots, Bland and Altman, and Passing and Bablok regression analyses respectively. The coefficient of variation was 5.07 % for pyrogallol red molybdate; 6.84 % for sulfosalicylic acid; 3.97 % for sulfosalicylic acid with sodium sulphate and 5.93 % for trichloroacetic acid methods. Bland and Altman analysis showed a bias of 5.8, 1.7 and ?5.4 for pyrogallol red molybdate versus sulfosalicylic acid, sulfosalicylic acid with sodium sulphate and trichloroacetic acid methods respectively. Passing and Bablok regression revealed a constant bias for pyrogallol red molybdate versus all turbidimetric methods but a proportional bias only with trichloroacetic acid method. Sulfosalicylic acid with sodium sulphate method is preferred to sulfosalicylic acid and trichloroacetic acid methods. 相似文献
2.
Lora Duki? Ana-Maria ?imundi? Davorin Malogorski 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2014,24(1):146-150
Introduction:
Sample type recommended by the manufacturer for the digoxin Abbott assay is either serum collected in glass tubes or plasma (sodium heparin, lithium heparin, citrate, EDTA or oxalate as anticoagulant) collected in plastic tubes. In our hospital samples are collected in plastic tubes. Our hypothesis was that the serum sample collected in plastic serum tube can be used interchangeably with plasma sample for measurement of digoxin concentration. Our aim was verification of plastic serum tubes for determination of digoxin concentration.Materials and methods:
Concentration of digoxin was determined simultaneously in 26 venous blood plasma (plastic Vacuette, LH Lithium heparin) and serum (plastic Vacuette, Z Serum Clot activator; both Greiner Bio-One GmbH, Kremsmünster, Austria) samples, on Abbott AxSYM analyzer using the original Abbott Digoxin III assay (Abbott, Wiesbaden, Germany). Tube comparability was assessed using the Passing Bablok regression and Bland-Altman plot.Results:
Serum and plasma digoxin concentrations are comparable. Passing Bablok intercept (0.08 [95% CI = −0.10 to 0.20]) and slope (0.99 [95% CI = 0.92 to 1.11]) showed there is no constant or proportional error.Conclusion:
Blood samples drawn in plastic serum tubes and plastic plasma tubes can be interchangeably used for determination of digoxin concentration. 相似文献3.
复值型数据Improper线性回归模型的估计(英文) 总被引：1，自引：0，他引：1
复随机变量称为"improper"随机变量,若它的"伪"协方差阵不为0,否则称为"proper"随机变量.研究了误差服从独立同分布的improper复高斯分布的线性回归模型.利用极大似然方法和2阶段最小二乘方法来估计回归系数.模拟表明,这2种方法与经典复版本的最小二乘法有不同之处,并将该方法用于实际风信号数据的处理. 相似文献
4.
Previous studies of academic web interlinking have tended to hypothesise that the relationship between the research of a university and links to or from its web site should follow a linear trend, yet the typical distribution of web data, in general, seems to be a non-linear power law. This paper assesses whether a linear trend or a power law is the most appropriate method with which to model the relationship between research and web site size or outlinks. Following linear regression, analysis of the confidence intervals for the logarithmic graphs, and analysis of the outliers, the results suggest that a linear trend is more appropriate than a non-linear power law. 相似文献
5.
Fatma Emel Kocak Bahadir Ozturk Ozben Ozden Isiklar Ozlem Genc Ali Unlu Irfan Altuntas 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(3):430-438
Introduction
Total 25-hydroxyvitamin D [25(OH)D] is the most reliable indicator of vitamin D status. In this study, we compared two automated immunoassay methods, the Abbott Architect 25-OH Vitamin D assay and the Roche Cobas Vitamin D total assay, with the liquid chromatography-tandem mass spectrometry (LC-MS/MS).Materials and methods
One hundred venous blood samples were randomly selected from routine vitamin D tests. Two of the serum aliquots were analyzed at the Abbott Architect i2000 and the Roche Cobas 6000’s module e601 in our laboratory within the same day. The other serum aliquots were analyzed at the LC-MS/MS in different laboratory. Passing-Bablok regression analysis and Bland-Altman plot were used to compare methods. Inter-rater agreement was analyzed using kappa (κ) analysis.Results
The Roche assay showed acceptable agreement with the LC-MS/MS based on Passing-Bablok analysis (intercept: -5.23 nmol/L, 95% CI: -8.73 to 0.19; slope: 0.97, 95% CI: 0.77 to 1.15). The Abbott assay showed proportional (slope: 0.77, 95% CI: 0.67 to 0.85) and constant differences (intercept: 17.08 nmol/L; 95% CI: 12.98 to 21.39). A mean bias of 15.1% was observed for the Abbott and a mean bias of -14.1% was observed for the Roche based on the Bland-Altman plots. We found strong to nearly perfect agreement in vitamin D status between the immunoassays and LC-MS/MS. (κ: 0.83 for Abbott, κ: 0.93 for Roche) using kappa analysis.Conclusion
Both immunoassays demonstrated acceptable performance, but the Roche Cobas assay demonstrated better performance than the Abbott Architect in the studied samples.Key words: 25-Hydroxyvitamin D, chromatography, immunoassay, methods, tandem mass spectrometry 相似文献6.
为了研究同行评议与指标体系评价结果之间的关系,本文基于《泰晤士报高等教育增刊》2007年世界大学排名数据,利用多元回归分析和Kappa一致性检验法进行了研究。研究发现,数据丰富程度影响同行评议与指标评价的一致性;在数据不足的情况下,辅以同行评议进行综合评价是较优的选择;可用回归拟合优度对数据丰富程度进行判断;同行评议也有其适用范围,权威的同行评议可以作为指标体系权重赋值以及指标选取的重要依据;在数据较为丰富的情况下可以向同行评议专家提供原始数据。 相似文献
7.
笔者首先通过文献研究和网络调查等定性分析方法梳理出科技产出能力的所有可能的影响因素,并在数据可获得性的前提下,以1996-2008年为时间维,采集科技产出能力及其影响因素的相关数据,然后对科技产出能力及其影响因素之间的相互关系进行二元相关分析,并利用多元线性回归分析方法从所有相关因素中筛选出影响程度较高的因素,构建科技产出能力的影响因素分析与预测模型。最后基于二元相关分析的结果,选择相关程度较高的因素,利用目前流行的BP神经网络预测方法对科技产出能力进行预测研究,并与多元回归分析预测模型的预测性能进行比较。 相似文献
8.
Nafija Serdarevic Pradeep Dabla Adina Elena Stanciu 《Indian journal of clinical biochemistry : IJCB》2021,36(2):151
Recent studies have shown that there are systematic differences among total and free prostate-specificantigen (PSA) immunoassays. In this study we analyzedintermethod differences in total PSA (tPSA) and free PSA(fPSA) measurement using ARCHITECT i2000SR (Abbott Diagnostics) and COBAS E601 (Roche Diagnostics). A number of 160 blood samples were tested for tPSA and 50 samples for fPSA (selecting only sampleswith tPSA: 4.1–10.0 μg/L). Passing–Bablok regression analysis was used to compare the two analytical methods fortPSA, fPSA and percentage of fPSA (%fPSA). A strong correlation was noticed between ARCHITECT i2000SR and COBAS E601 for tPSA, fPSA and %fPSA (r between 0.94 and 0.99). Concentrations of tPSA and fPSA measured by COBAS E601 were higher thanthose measured by ARCHITECT i2000SR with a bias of 0.8 μg/L for tPSA and 0.14 μg/L for fPSA. Analyzing therelative difference between methods for fPSA and %fPSA, COBAS E601 exceed a 10% relative difference limit. Our study confirms that there are differences in measured concentrations of tPSA and fPSA byvarious commercial methods. Because clinical judgment on subsequent diagnostic procedures, such as prostatebiopsy, is based on tPSA and fPSA results, tests harmonization should be a priority. 相似文献
9.
针对平均坡度指标难以稳健描述地面坡谱特征的问题,提出一种基于频率累加分位归并的坡谱分级方法。作为验证,运用数字高程模型数据将全国县域分为5个坡级,借助2000年和2020年人口普查数据分析了坡级与人口分布的关系。结果发现：①所提出的分级方法包含频率累加曲线的构建、基于分位数的参考曲线生成、基于相似度的类型归并3个关键步骤,由此得到的全国县域坡级划分方案具备稳健坡度梯度性、宏观空间连片性以及清晰地学含义。②全国县域人口数量总体保持随坡级升高而波动式缩小的特征,且二者间呈现明显的线性负相关关系,线性拟合R2从2000年的0.761上升到了2020年的0.845,20年间人口总数变化量与坡级的线性拟合R2达0.963;人口密度的极端值对其自身的坡级分布有较大影响,当剔除人口密度小于20人/km2和大于2000人/km2的区域后,两个分析年份全国县域人口密度均稳健保持着随坡级升高而线性减小（R2 > 0.985）。本文为稳健表达如坡度等环境梯度提供了一种新的可行分级方法,并深化了对中国县域人口分布与坡度关系的认识。 相似文献
10.
在相关研究成果和薪酬激励理论的基础上,提出高管年薪与高管规模、企业绩效指标之间的关系以及高管持股比例与企业绩效指标之间关系的假设。以2004-2006年中国上市信息技术企业作为样本企业,并选取变量,采用了多元回归分析方法来检验高管年薪与高管规模、企业绩效指标之间的关系,再同时采用了线性与非线性来检验高管持股比例与企业绩效指标之间的关系。在实证研究的结果基础上,提出了一些建议。 相似文献
11.
本文利用黄淮平原253个县1983－1989年农业生产的时间序列数据，采用多元回归和逐步回归方法分析了种植业产值波动与主要作物总产波动、各作物的总产波动与单产、播种面积波动在时间和空间上变化的相关关系；并进一步分析了原因和提出了稳定种植业生产的建议。 相似文献
12.
Davide Giavarina 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(2):141-151
In a contemporary clinical laboratory it is very common to have to assess the agreement between two quantitative methods of measurement. The correct statistical approach to assess this degree of agreement is not obvious. Correlation and regression studies are frequently proposed. However, correlation studies the relationship between one variable and another, not the differences, and it is not recommended as a method for assessing the comparability between methods.
In 1983 Altman and Bland (B&A) proposed an alternative analysis, based on the quantification of the agreement between two quantitative measurements by studying the mean difference and constructing limits of agreement.
The B&A plot analysis is a simple way to evaluate a bias between the mean differences, and to estimate an agreement interval, within which 95% of the differences of the second method, compared to the first one, fall. Data can be analyzed both as unit differences plot and as percentage differences plot.
The B&A plot method only defines the intervals of agreements, it does not say whether those limits are acceptable or not. Acceptable limits must be defined a priori, based on clinical necessity, biological considerations or other goals.
The aim of this article is to provide guidance on the use and interpretation of Bland Altman analysis in method comparison studies.Key words: Bland-Altman, agreement analysis, laboratory research, method comparison, correlation of data 相似文献
In 1983 Altman and Bland (B&A) proposed an alternative analysis, based on the quantification of the agreement between two quantitative measurements by studying the mean difference and constructing limits of agreement.
The B&A plot analysis is a simple way to evaluate a bias between the mean differences, and to estimate an agreement interval, within which 95% of the differences of the second method, compared to the first one, fall. Data can be analyzed both as unit differences plot and as percentage differences plot.
The B&A plot method only defines the intervals of agreements, it does not say whether those limits are acceptable or not. Acceptable limits must be defined a priori, based on clinical necessity, biological considerations or other goals.
The aim of this article is to provide guidance on the use and interpretation of Bland Altman analysis in method comparison studies.Key words: Bland-Altman, agreement analysis, laboratory research, method comparison, correlation of data 相似文献
13.
赵超 《中国科学院研究生院学报》2010,27(4):556-562
用于估计马斯京根模型参数的方法很多,但这些方法在数据存在异常值时缺乏抵御异常值影响的抗差性能. 推导出一种有限制条件的参数抗差估计算法,通过含有随机误差和异常误差的人工数据和真实数据比较抗差算法与传统最小二乘算法的抗差性. 研究表明抗差估计算法能减小异常值对参数估值的影响. 相似文献
14.
A modified theory is proposed for extracting cell dielectric properties from the peak frequency measurement of electrorotation (ER) and the crossover frequency measurement of dielectrophoresis (DEP). Current theory in the literature is based on the low frequency (DC) approximations for the equivalent cell permittivity and conductivity, which are valid when the measurements are performed in a medium with conductivity less than 1 mS/m. The present theory extracts the cell properties through optimizing an expression for the medium conductivity in terms of the peak ER, or DEP crossover, frequency according to its definition using full expressions of equivalent cell permittivity and conductivity. Various levels of approximation of the theory are proposed and discussed through a scaling analysis. The present theory can extract both membrane and interior properties from the low and the high peak ER, or DEP crossover, frequencies for any medium conductivity provided the peak ER, or DEP crossover, frequency exists. It can be reduced to the linear theory for the low peak ER and DEP crossover frequencies in the literature when the medium conductivity is less than 10 mS/m. However, we can determine the membrane capacitance and conductance via the slope and intercept, respectively, of the straight line fitting of the ER peak and DEP frequency against medium conductivity data according to the linear theory only when the intercept dominates the experimental uncertainty, which occurs when the medium conductivity is less than 1 mS/m in practice. 相似文献
15.
《Journal of The Franklin Institute》2023,360(10):6929-6952
Self-driving vehicles must be equipped with path tracking capability to enable automatic and accurate identification of the reference path. Model Predictive Controller (MPC) is an optimal control method that has received considerable attention for path tracking, attributed to its ability to handle control problems with multiple constraints. However, if the data acquired for determining the reference path is contaminated by non-Gaussian noise and outliers, the tracking performance of MPC would degrades significantly. To this end, Correntropy-based MPC (CMPC) is proposed in this paper to address the issue. Different from the conventional MPC model, the objective of CMPC is constructed using the robust metric Maximum Correntropy Criterion (MCC) to transform the optimization problem of MPC to a non-concave problem with multiple constraints, which is then solved by the Block Coordinate Update (BCU) framework. To find the solution efficiently, the linear inequality constraints of CMPC are relaxed as a penalty term. Furthermore, an iterative algorithm based on Fenchel Conjugate (FC) and the BCU framework is proposed to solve the relaxed optimization problem. It is shown that both objective sequential convergence and iterate sequence convergence are satisfied by the proposed algorithm. Simulation results generated by CarSim show that the proposed CMPC has better performance than conventional MPC in path tracking when noise and outliers exist. 相似文献
16.
指出失业预警系统的建模是一个小样本、高维度、非线性、存在噪音数据的复杂的建模问题,重点探讨了基于回归分析技术对失业预警系统进行建模的理论、方法与步骤。讨论了常见的缺失数据处理、数据归一化以及特征降维等数据预处理方法;进一步分析了最小二乘回归、Logistic回归、岭回归、BP神经网络以及支持向量回归五种回归技术;最后基于广东省的社会经济调查数据对五种回归方法进行了实证分析,实验结果表明:在对失业率的预测上,支持向量回归预测效果最好,最小二乘回归、岭回归与BP神经网络次之,Logistic回归预测效果最差。 相似文献
17.
A binary approach to data storage and retrieval is introduced. It views the data base as a two-dimensional matrix that relates entities to all possible values the attributes of these entities may take. As such, it provides a unified solution to the two conflicting types of data base transactions—operational and managerial. An analytical investigation of the feasibility of binary storage and a compression method for reducing meaningless areas of the matrix are presented. Storage efficiencies of binary and conventional inverted file methods are compared and evaluated. An analysis of retrieval considerations associated with the binary matrix is given, particularly the issue of going from high to low orders of compression. Results of these analyses indicate that the binary data base's efficiency increases with increases in query complexity. Future research directions are sited and discussed. 相似文献
18.
长江上游川江段气温、降水及径流变化趋势分析 总被引：9，自引：4，他引：5
本文运用Mann-Kendall统计检验、线性倾向估计和小波分析等方法对长江上游川江段气象水文要素的长期变化趋势及周期性进行了分析。研究表明：①川江段气温、径流呈不同程度的减少趋势,而降水则呈小幅度增加趋势,年变化率分别为气温-0.0017℃、降水0.3023mm、宜昌径流-6.6668m3/s、寸滩径流-9.5840m3/s,其中寸滩径流量减少趋势十分显著,通过了5%显著水平的信度检验;②川江段气温、降水、径流序列具有不同的周期成分,如年平均气温具有4年、8年和23年主周期,年降水具有3年、6年和16年主周期,寸滩站径流具有3年、8年和16年主周期,宜昌站径流具有3年、16年和45年主周期,且在时域分布上也是不均匀的;③另一方面,在气温略有降低、降水略有增加的气候组合下,川江段径流却呈现减小的变化趋势,同时川江段寸滩站和宜昌站的年径流量从20世纪90年代后期至今在变化特征上也表现出相反的趋势,这是因为人类活动所致还是气候变化影响所致,还有待深入研究。 相似文献
19.
20.
为了提高高维数据集合离群数据挖掘效率,在分析了传统的离群数据挖掘算法优点和缺点的基础上,提出了一种离群点检测算法,首先将非线性问题转化为高维特征空间中的线性问题,然后利用非线性数据变换进行维数约减,对从高维采样数据中恢复得到低维数据集,通过本文提出的离群数据假设,并结合本文给出的离群聚类方法对所得数据对象投影分量是否是离群数据进行判别。仿真实验的结果表明了该方法能够有效地发现高维数据集中的离群点。与此同时,该算法具有参数估计简单、参数影响不大等优点,为离群点检测问题的机器学习提供了一条新的途径。 相似文献