Wolda Henk
Smithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Republic of Panama.
Oecologia. 1981 Sep;50(3):296-302. doi: 10.1007/BF00344966.
The effect of sample size and species diversity on a variety of similarity indices is explored. Real values of a similarity index must be evaluated relative to the expected maximum value of that index, which is the value obtained for samples randomly drawn from the same universe, with the diversity and sample sizes of the real samples. It is shown that these expected maxima differ from the theoretical maxima, the values obtained for two identical samples, and that the relationship between expected and theoretical maxima depends on sample size and on species diversity in all cases, without exception. In all cases but one (the Morisita index) the expected maxima depend strongly to fairly strongly on sample size and diversity. For some of the more useful indices empirical equations are given to calculate the expected maximum value of the indices to which the observed values can be related at any combination of sample sizes. It is recommended that the Morisita index be used whenever possible to avoid the complex dealings with effects of sample size and diversity; however, when previous logarithmic transformation of the data is required, which often may be the case, the Morisita-Horn or the Renkonen indices are recommended.
探讨了样本大小和物种多样性对各种相似性指数的影响。相似性指数的实际值必须相对于该指数的预期最大值进行评估，预期最大值是从具有实际样本的多样性和样本大小的同一总体中随机抽取的样本所获得的值。结果表明，这些预期最大值不同于理论最大值（两个相同样本所获得的值），并且预期最大值与理论最大值之间的关系在所有情况下毫无例外地都取决于样本大小和物种多样性。在除一种情况（森下指数）之外的所有情况下，预期最大值都强烈到相当强烈地取决于样本大小和多样性。对于一些更有用的指数，给出了经验方程，用于计算在任何样本大小组合下观测值可与之相关的指数的预期最大值。建议尽可能使用森下指数，以避免处理样本大小和多样性影响的复杂情况；然而，当需要对数据进行先前的对数变换时（这种情况经常发生），建议使用森下 - 霍恩指数或伦科宁指数。
