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91.
针对普通的常系数线性回归模型存在预测误差较大的缺陷,对Hildreth-Houck模型进行修正,得到带跳的线性回归模型(LRMJ),对该模型中各参数进行估计,并对模型中被解释变量的数学期望与方差等统计性质进行讨论.最后将该模型运用于一个实际问题,证明该模型不仅可行而且能够得到比普通常系数线性回归模型更为精确的预测值。 相似文献
92.
The influence of scale and the spatial characteristics of landscapes on land-cover mapping using remote sensing 总被引:14,自引:1,他引:13
Statistical analyses provide a means for assessing relationships between landscape spatial pattern and errors in the estimates of cover-type proportions as land-cover data are aggregated to coarser scales. Results from a multiple-linear regression model suggest that as patch sizes, variance/mean ratio, and initial proportions of cover types increase, the proportion error moves in a positive direction and is governed by the interaction of the spatial characteristics and the scale of aggregation. However, the standard linear model does not account for the different directions of scale-dependent proportion error since some classes become larger and others become smaller as the scene is aggregated. Addition of indicator variables representing class-type significantly improves the performance by allowing the model to respond differently to different classes. A regression tree model provides a much simpler fit to the complex scaling behavior through an interaction between patch size and aggregation scale. An understanding of the relationships between landscape pattern, scale, and proportion error may advance methods for correcting land-cover area estimates. Such methods could also facilitate high-resolution calibration and validation of coarse-scale remote-sensing-based land-cover mapping algorithms. Ongoing initiatives to produce global land-cover datasets from remote sensing, such as efforts within the IGBP and the EOS MODIS Land-Team, include significant emphasis on high level calibration and validation activities of this nature. 相似文献
93.
油罐中石油及其液体产品的平均温度测量不准,将直接影响着液体体积的测量精度。从油罐储量对温度测量的要求出发,介绍了铜热电阻平均温度传感器的结构,通过理论分析,指出了提高精度的途径。 相似文献
94.
以朗伯——比尔定律为依据,用统计学的原理,探讨了建立的三个工作曲线方程的误差与准确性。结果表明:线性回归方程、过原点线性回归方程和座标原点与平均数之连线方程在实验误差较小的情况下,基本趋于一致,均能作为工作曲线方程使用。其中以座标原点与平均数之连线方程的重现性最佳,建立方程的方法简单,所以在比色分析中可认为是建立工作曲线方程的可靠方法。 相似文献
95.
梁淑云 《西南大学学报(自然科学版)》1996,18(5):447-453
本文用应用统计微分法,对测量6误差模型中未知真值x的标准差的估计σx,误差方差的估计Svv,参数β1函数的估计γ1l与θ的极限分布进行了探讨与研究。 相似文献
96.
Harr KE Raskin RE Heard DJ 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2005,34(4):383-388
BACKGROUND: Few studies have been done to evaluate anticoagulants for use with blood samples from birds and reptiles. Heparin currently is the most commonly used anticoagulant in practice, but may adversely affect blood cell staining and quantitation. OBJECTIVE: The purpose of this study was to evaluate the effects of lithium heparin, K3-EDTA, and sodium citrate, with and without the addition of albumin, on hematologic variables in macaw (Ara sp) and python (Python molurus bivittatus) blood samples. METHODS: Blood samples from 10 macaws and 10 Burmese pythons were collected in heparin-coated syringes and placed into tubes containing either lithium heparin, K3-EDTA, or sodium citrate with and without the addition of 0.25 mL of a 22% bovine serum albumin solution. Cell lysis was determined by counting the number of lysed cells/200 WBCs in Wright's-Giemsa-stained blood smears and by qualitative evaluation of pink plasma in microhematocrit tubes. A CBC was done after 3, 12, and 24 hours of storage at 4 degrees C in anticoagulant-containing tubes and results were compared with those obtained at 0 hour for the heparin-coated syringe sample. A biochemical panel also was done at each time point in similarly stored lithium-heparin samples. RESULTS: Hemolysis was significantly increased in citrated samples from both macaws and pythons beginning at 12 hours. At 24 hours, 19 of 30 (63%) macaw samples in all anticoagulants had >100 lysed cells/200 WBCs. There were no significant differences in hematologic values in samples from pythons collected in heparin or EDTA at any time point. No significant differences were found in the number of lysed cells or in other hematologic data in samples with albumin. Glucose concentration decreased and potassium concentration increased significantly over time in heparinized blood samples. CONCLUSIONS: Based on the results of this study, whole blood samples anticoagulated with lithium heparin or EDTA should be evaluated within 12 hours (macaws) or 24 hours (pythons) of collection and stored at 4 degrees C for best results. Citrate should be avoided as it may result in increased cell lysis. The addition of albumin does not prevent cell lysis. 相似文献
97.
油松毛虫卵(块)和蛹种群简单随机抽样最适样方大小的确定方法 总被引:1,自引:0,他引:1
在种群空间格局的研究的基础上,采用7种方法对同松毛虫卵(块)和蛹种群简单随机抽样技术中最适样方大小的确定问题进行了研究,结果表明,无论是卵(块)抑或蛹种群,都是在u=1时抽样误差最低,即以单株油松为样方时最为适宜,此外,文中还列出了考虑抽样花费时确定最适样方式大小的各种方法,并讨论了有关问题。 相似文献
98.
99.
100.
Bente Flatland Kathleen P. Freeman Linda M. Vap Kendal E. Harr 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2013,42(4):405-423
Point‐of‐care testing (POCT) refers to any laboratory testing performed outside the conventional reference laboratory and implies close proximity to patients. Instrumental POCT systems consist of small, handheld or benchtop analyzers. These have potential utility in many veterinary settings, including private clinics, academic veterinary medical centers, the community (eg, remote area veterinary medical teams), and for research applications in academia, government, and industry. Concern about the quality of veterinary in‐clinic testing has been expressed in published veterinary literature; however, little guidance focusing on POCT is available. Recognizing this void, the ASVCP formed a subcommittee in 2009 charged with developing quality assurance (QA) guidelines for veterinary POCT. Guidelines were developed through literature review and a consensus process. Major recommendations include (1) taking a formalized approach to POCT within the facility, (2) use of written policies, standard operating procedures, forms, and logs, (3) operator training, including periodic assessment of skills, (4) assessment of instrument analytical performance and use of both statistical quality control and external quality assessment programs, (5) use of properly established or validated reference intervals, (6) and ensuring accurate patient results reporting. Where possible, given instrument analytical performance, use of a validated 13s control rule for interpretation of control data is recommended. These guidelines are aimed at veterinarians and veterinary technicians seeking to improve management of POCT in their clinical or research setting, and address QA of small chemistry and hematology instruments. These guidelines are not intended to be all‐inclusive; rather, they provide a minimum standard for maintenance of POCT instruments in the veterinary setting. 相似文献