The estimation of statistical parameters for local alignment score distributions
The estimation of statistical parameters for local alignment score distributions
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DOI：
10.1093/nar/29.2.351
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发表时间：
2001-01-15
影响因子：
14.9
通讯作者：
Hwa, T
中科院分区：
文献类型：
--
作者：
Altschul, SF;Bundschuh, R;Hwa, T
随机序列的最优局部比对得分的分布在评价序列比对的统计显著性方面起着至关重要的作用，这些得分可以很好地用极值分布来描述。分布的参数取决于所采用的评分系统和随机字母频率;一般来说，它们不能通过分析得出，但必须通过曲线拟合来估计。为了获得准确的参数估计，最近描述的“岛”方法的形式有几个优点。我们详细描述了这种方法，并使用它来研究这些参数对有限长度边缘效应的函数依赖性。
The distribution of optimal local alignment scores of random sequences plays a vital role in evaluating the statistical significance of sequence alignments, These scores can be well described by an extreme-value distribution. The distribution's parameters depend upon the scoring system employed and the random letter frequencies; in general they cannot be derived analytically, but must be estimated by curve fitting. For obtaining accurate parameter estimates, a form of the recently described 'island' method has several advantages. We describe this method in detail, and use it to investigate the functional dependence of these parameters on finite-length edge effects.