雅虎和微软都认为，基于未公开的内部测定统计，他们搜索引擎的搜索结果和Google的质量相差无几。
Both Yahoo and Microsoft contend that their search engines' results have achieved parity in quality with Google's, based on internal statistical measurements that they do not disclose publicly.
氨基酸替代数的估计是测定蛋白质分子间进化距离的基本统计方法，是研究蛋白质分子进化的基础。
Estimating of substitution number of amino acids is basic statistic methods of measuring evolution distance between proteins, which is the base of researching molecular evolution of protein.
由于系统方程是时变的，在测量过程中，系统噪声和观测噪声的统计特性等很难精确地估计或测定，事实上很多误差模型都不能简单的设为白噪声。
Because the system equation is changed with time, during the measurement, the statistic character of the system noise and the observation noise cannot be estimated or be determined accurately.
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