Accuracy Evaluation Of Methods Research Articles

Accuracy evaluation of methods and techniques in Web-based question answering systems: a survey

Question answering (QA) systems answer the queries of users efficiently in the least amount of time. A researcher has to decide which among various methods and techniques available will be used to retrieve accurate answers when developing a QA system. This step creates an overhead before making a selection. The study highlights the methods and techniques that perform well in terms of the accuracy of answers provided. Nine Web-based question answering systems were consulted, and the applied methods and techniques evaluated on the basis of the percentage of questions correctly answered and the mean reciprocal rank evaluation measures. Results were discussed using three key stages involved in a QA system: answer extraction, scoring of answers, and answer aggregation. Results show some techniques have higher accuracy of answers than others. Not all methods in QA systems can improve the accuracy of answers individually, but the methods used in combination obtain greater effect. The results can be used to select methods and techniques optimal for producing highly accurate scores without spending time on benchmarking.

MEASUREMENT OF NITROUS OXIDE IN A NITROGEN MATRIX USING GAS CHROMATOGRAPHY WITH MICROELECTRON CAPTURE DETECTION: VALIDATION OF ANALYTICAL METHOD

Atmospheric nitrous oxide (N2O) as one of the most potent greenhouse gases significantly contributes to the global warming effect. Therefore, an accurate and valid measurement method for monitoring its environmental release is of great importance. In this study, an analytical method for the measurement of N2O in a nitrogen (N2) matrix using gas chromatography and microelectron capture detection (GC‐μECD) has been validated. The analytical method was validated in terms of some performance parameters such as system suitability, precision (repeatability and reproducibility), linearity, limit of detection (LoD) and limit of quantitation (LoQ), accuracy and method robustness. The results show that the GC system was found to be suitable for the measurement of N2O in the N2 matrix. The repeatability and reproducibility of the method were found to have %RSD of 1.42 and 0.71, respectively, indicating that the method is repeatable and reproducible for N2O measurement. The linearity of the method was excellent, having the R2 value of 0.9998. The LoD and LoQ of the method were found to be 0.10 and 0.34 µmol mol-1, respectively. Evaluation of method accuracy showed that the method is also accurate for the measurement of N2O in the N2 matrix. The method’s roughness indicated that the method was quite stable and unaffected by slight changes in the experimental conditions. From this study, it can be concluded that the validated method can be used in testing laboratory for internal quality assurance programs purposes related to the measurement of N2O in N2 matrix.

Review of Thirteen Years of CTS Winery Laboratory Collaborative Data

Data from 13 years (78 wines) of wine industry laboratory proficiency testing were reviewed. After outlier removal, within-laboratory precision (repeatability) and across-laboratory precision (reproducibility) were determined for measurements of alcohol, titratable acidity, volatile acidity, total SO₂, free SO₂, malic acid, specific gravity, pH, residual sugar, glucose plus fructose, and absorbance at 420 and 520 nm. Reproducibility was 3.6 to 57.8 times higher than repeatability. Reproducibility was evaluated with Horwitz ratios (HorRat); only alcohol, titratable acid, and total SO₂ had acceptable values (mean HorRat <2). Measurement z scores demonstrated non-normal distributions, particularly for specific gravity, likely due to confounding with density. Reproducibility did not vary significantly over time, with exceptions: imprecision of ethanol measurements decreased (improved) by 0.0084% v/v per year, while the imprecision of titratable acidity, pH, and malic acid measurements increased by 0.0089 g/L as tartaric, 0.0008 pH units, and 0.13 g malic acid/L per year, respectively. The imprecision of reproducibility and repeatability generally increased with analyte concentration, with notable exceptions for alcohol (both), volatile acidity (reproducibility), and total SO₂ (repeatability). The methods or instruments used to determine alcohol, titratable acidity, free and total SO₂, and volatile acidity changed significantly over time. Significant differences were observed among techniques for many analytes, which can be rationalized by attribution to well-known matrix effects manageable in a properly run method; e.g., higher apparent concentrations of alcohol by boiling point methods in high-sugar matrices. Evaluation of method accuracy was not possible due to the lack of wine reference materials with known true values. Results demonstrate the need for industry-wide improvement in analytical performance for some assays, and the potential benefit of adopting criteria guidelines for method performance.

Determination of metals in soft drinks packed in different materials by ETAAS

The present work proposes a method for the direct determination of Al, Cu, Cr, Fe and Ni in Brazilian carbonated soft drinks by electrothermal atomic absorption spectrometry (ETAAS). Samples of different flavors packed in containers made of different materials (polyterephthalate ethylene and glass bottles, and aluminum and steel cans) were analyzed. The method was optimized by building up pyrolysis and atomization curves in sample medium and by evaluating the calibration approach. Under optimized conditions, recoveries in the range of 92–104% were obtained in the evaluation of method accuracy. The limits of quantification for Al, Cu, Cr, Fe and Ni were 2.3, 0.93, 0.17, 0.90 and 1.2μgL−1, respectively. Also, the impact of the material used in the packaging and flavor on the concentrations of each metal in the samples was evaluated. It was proved that neither flavor nor packaging material affected the concentrations of Al and Fe in the samples. On the other hand, the packaging material influenced the concentration of Cu, Cr and Ni, and only the flavor affected the concentration of Cu in the samples. These conclusions were based on the data obtained from the application of a two-way ANOVA evaluation at 95% confidence level.

基于知识库的像斑光谱向量相似度土地覆盖变化检测方法

土地利用/覆盖变化检测是国内外全球化进程研究的重要内容,选择适当的变化检测方法对西北地区土地利用/覆盖变化进行研究在"生态十年项目"中具有重要的意义.选择西北地区具有典型代表性的TM轨道号134033区域作为变化检测方法验证的试验区,采用2005和2010年两期Landsat TM影像,在eCognition Developer 8.64软件支持下,采用基于像斑的光谱特征特征向量相似度方法进行变化检测,并利用2010年土地覆盖数据作为先验知识库对变化区域分类,提取土地利用/覆盖变化信息,并对变化结果进行定量分析.结果表明,采用基于像斑的光谱特征特征向量相似度方法对于试验区的土地利用/覆盖变化制图具有检测快速、检测精度高等优点,适合试验区以及整个西北地区的土地利用/覆盖变化的检测.最终采用该方法以及分类后比较法获得了西北地区2000-2010年近10年的土地利用/覆盖分类图.;Land use/cover change (LUCC) is an important field of global and local environmental change research. LUCC and its corresponding effects have a direct impact on the environment and ecological processes, and in turn natural resources management and related decisions. In China, LUCC research is at the core of all issues related to sustainable development, with tremendous practical significance. Remote sensing imagery change detection has great application value in many areas, such as the survey of land-use change, urban expansion, and vegetation resource monitoring. The choice of an effective change detection method for a given study area is a central issue of such detection. In research conducted in various countries, remote sensing imagery change detection methods have transitioned from pixel level to feature level and knowledge level. Currently used LUCC detection methods are in two categories, direct spectrum comparison and comparison of classification results. The spectrum feature vector of a segment in a Landsat Thematic Mapper (TM) image can be regarded as a vector of six-dimensional feature space. If the angle between two vectors is smaller and vector mode closer, the more similar are the two vectors. Thus, we used the cosine of the angle between two vectors and the ratio of vector mode to establish a vector similarity index for measuring vector similarity. Combined with the National Change of Ecological Environment Decade (2000-2010) Remote Sensing Survey and Assessment project, jointly organized and implemented by the Ministry of Environmental Protection and Chinese Academy of Sciences, this paper focuses on application of a change detection method. This method uses segment similarity of a spectrum vector based on a knowledge base in the northwest region. There is also an evaluation of method accuracy. The area covered by TM path 134 row 33, representative of the northwest region, was chosen as a change detection method validation test site. We used 2005 and 2010 two-phase Landsat TM imagery to detect land-cover change, using spectrum vector similarity based on a segment with support from eCognition Developer 8.64 software. We used 2010 land-cover data as a priori knowledge base to classify regions of change. The results showed the following. 1) Segment similarity of the spectrum vector method is appropriate for change detection in the northwest region, and accuracy of the 2005 land-cover database established using the 2010 land-cover database as a priori knowledge was relatively high. 2) The method of segment similarity of the spectrum vector has many advantages, such as less computation, fast operation, and suitability for large-scale rapid change detection. 3) The method is more effective for farmland, water, built-up land and vegetation cover change. 4) Accuracy of the land-cover database established by change detection depends on accuracy of the baseline land-cover database. Compared with the latter database, accuracy of the former database declined slightly. The main cause of this decline is change that was difficult to detect and change area misclassification, attributable to land-cover types with similar spectral features such as lakes and reservoirs, bare land, and sparse vegetation. 5) Because of the effects of imagery phase and cloud coverage, the land-cover database established by change detection requires additional manual modifications to improve its accuracy.