Confidence intervals on stratigraphic ranges: partial relaxation of the assumption of randomly distributed fossil horizons
Confidence intervals on stratigraphic ranges: partial relaxation of the assumption of randomly distributed fossil horizons
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DOI：
10.1017/s0094837300012938
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发表时间：
1994-10
期刊：
影响因子：
2.7
通讯作者：
C. Marshall
中科院分区：
文献类型：
--
作者：
C. Marshall
经典的地层范围端点置信区间计算公式是基于化石发现随机分布的限制性假设。本文提出了一种计算地层范围端点置信区间的方法，该方法在一定程度上放宽了这一假设：该方法适用于任何间隙大小的连续分布，而不仅仅是那些由随机过程产生的分布。新方法的通用性所付出的代价是双重的：(1)与置信区间的大小有关的不确定性；(2)对于较大的置信值（例如，95%），需要丰富的化石记录为相应的置信区间设定上限。这种新方法并不普遍；与计算经典置信区间的方法一样，它是建立在间隙大小与地层位置之间没有相关性的假设基础上的。用新方法对加勒比海新近系苔藓虫类的化石记录进行了分析。这里开发的方程，就像那些经典的置信区间一样，不应该应用于基于离散采样制度的地层范围，比如那些典型的从深海钻探岩心建立的地层范围，尽管这条规则也有例外。
The equations for calculating classical confidence intervals on the end points of stratigraphic ranges are based on the restrictive assumption of randomly distributed fossil finds. Herein, a method is presented for calculating confidence intervals on the end-points of stratigraphic ranges that partially relaxes this assumption: the method will work for any continuous distribution of gap sizes, not just those generated by random processes. The price paid for the generality of the new approach is twofold: (1) there are uncertainties associated with the sizes of the confidence intervals, and (2) for large confidence values (e.g., 95%) a rich fossil record is required to place upper bounds on the corresponding confidence intervals. This new method is not universal; like the method for calculating classical confidence intervals it is based on the assumption that there is no correlation between gap size and stratigraphic position. The fossil record of the Neogene Caribbean bryozoan Metrarabdotos is analyzed with the new approach. The equations developed here, like those for classical confidence intervals, should not be applied to stratigraphic ranges based on discrete sampling regimes, such as those typically established from deep-sea drilling cores, though there are exceptions to this rule.