MEASURES OF THE AMOUNT OF ECOLOGIC ASSOCIATION BETWEEN SPECIES
MEASURES OF THE AMOUNT OF ECOLOGIC ASSOCIATION BETWEEN SPECIES
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DOI：
10.2307/1932409
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发表时间：
1945-01-01
期刊：
影响因子：
4.8
通讯作者：
DICE, LR
中科院分区：
文献类型：
--
作者：
DICE, LR
福布斯的关联系数表示关联度。两个特定物种之间的关联与AMT相比。他们之间的联系是偶然的。提供一个简单直接的测量amt。提出了一个种与另一种的联结指数。如果a是一个给定系列中出现A种的随机样本数，h是另一个种B与A一起出现的样本数，则联结指数B/A = h/a。类似地，如果B是出现sp. B的样本数，则关联指数A/B = h/B。还提出了一个符合指数2 h/（a + B），其值介于两个互反关联指数之间。作为对给定系列的样本与amt的偏差的统计可靠性的度量。对于偶然预期的关联，可以使用卡方检验。
The coefficient of association of Forbes indicates the amt. of association between 2 given spp. compared to the amt. of association between them expected by chance. To provide a simple direct measure of the amt. of association of one sp. with another, the association index is proposed. If a is the number of random samples of a given series in which sp. A occurs and h is the number of samples in which another species B occurs together with A, then the association index B/A = h/a. Similarly, if b is the number of samples in which sp. B occurs, then the association index A/B = h/b. There is also proposed a coincidence index, 2h/(a + b), whose value is intermediate between the 2 reciprocal association indices. As a measure of the statistical reliability of the deviation shown by the samples of a given series from the amt. of association expected by chance, the chi-square test may be used.