In large sample studies where distributions may be skewed and not readily transformed to symmetry, it may be of greater interest to compare different distributions in terms of percentiles rather than means. For exampl...In large sample studies where distributions may be skewed and not readily transformed to symmetry, it may be of greater interest to compare different distributions in terms of percentiles rather than means. For example, it may be more informative to compare two or more populations with respect to their within population distributions by testing the hypothesis that their corresponding respective 10th, 50th, and 90th percentiles are equal. As a generalization of the median test, the proposed test statistic is asymptotically distributed as Chi-square with degrees of freedom dependent upon the number of percentiles tested and constraints of the null hypothesis. Results from simulation studies are used to validate the nominal 0.05 significance level under the null hypothesis, and asymptotic power properties that are suitable for testing equality of percentile profiles against selected profile discrepancies for a variety of underlying distributions. A pragmatic example is provided to illustrate the comparison of the percentile profiles for four body mass index distributions.展开更多
The meteorological measurement automatic temperature testing system has a defective image. To solve the problem such as noise and insufficient contrast, and put forward the research program for image pretreatment, the...The meteorological measurement automatic temperature testing system has a defective image. To solve the problem such as noise and insufficient contrast, and put forward the research program for image pretreatment, the median filter, histogram equalization and image binarization, methods were used to remove noise and enhance images. Results showed that feature points were clear and accurate after the experiment. This simulation experiment prepared for the follow-up subsequent recognition process.展开更多
采用静态急性毒性试验法对江黄颡鱼进行研究。5种常见农药对江黄颡鱼苗24 h LC50半致死质量浓度、48 h LC50半致死质量浓度、安全质量浓度分别为:阿维菌素0.43、0.28、0.035 mg/L;草甘磷15.38、13.43、3.072 mg/L;啶虫咪0.13、0.09、0.0...采用静态急性毒性试验法对江黄颡鱼进行研究。5种常见农药对江黄颡鱼苗24 h LC50半致死质量浓度、48 h LC50半致死质量浓度、安全质量浓度分别为:阿维菌素0.43、0.28、0.035 mg/L;草甘磷15.38、13.43、3.072 mg/L;啶虫咪0.13、0.09、0.013 mg/L;百草枯4.62、3.720、.724 mg/L;复方胶悬剂550、3895、8.38 mg/L。常用农药的敏感性依次为:啶虫咪>阿维菌素>百草枯>草甘磷>复方胶悬剂。展开更多
文摘In large sample studies where distributions may be skewed and not readily transformed to symmetry, it may be of greater interest to compare different distributions in terms of percentiles rather than means. For example, it may be more informative to compare two or more populations with respect to their within population distributions by testing the hypothesis that their corresponding respective 10th, 50th, and 90th percentiles are equal. As a generalization of the median test, the proposed test statistic is asymptotically distributed as Chi-square with degrees of freedom dependent upon the number of percentiles tested and constraints of the null hypothesis. Results from simulation studies are used to validate the nominal 0.05 significance level under the null hypothesis, and asymptotic power properties that are suitable for testing equality of percentile profiles against selected profile discrepancies for a variety of underlying distributions. A pragmatic example is provided to illustrate the comparison of the percentile profiles for four body mass index distributions.
文摘The meteorological measurement automatic temperature testing system has a defective image. To solve the problem such as noise and insufficient contrast, and put forward the research program for image pretreatment, the median filter, histogram equalization and image binarization, methods were used to remove noise and enhance images. Results showed that feature points were clear and accurate after the experiment. This simulation experiment prepared for the follow-up subsequent recognition process.
文摘采用静态急性毒性试验法对江黄颡鱼进行研究。5种常见农药对江黄颡鱼苗24 h LC50半致死质量浓度、48 h LC50半致死质量浓度、安全质量浓度分别为:阿维菌素0.43、0.28、0.035 mg/L;草甘磷15.38、13.43、3.072 mg/L;啶虫咪0.13、0.09、0.013 mg/L;百草枯4.62、3.720、.724 mg/L;复方胶悬剂550、3895、8.38 mg/L。常用农药的敏感性依次为:啶虫咪>阿维菌素>百草枯>草甘磷>复方胶悬剂。
