Bejder L, Fletcher D, BrÄger S
Department of Marine Science, University of Otago
Anim Behav. 1998 Sep;56(3):719-725. doi: 10.1006/anbe.1998.0802.
Association indices were originally developed to describe species co-occurrences, but have been used increasingly to measure associations between individuals. However, no statistical method has been published that allows one to test the extent to which the observed association index values differ from those of a randomly associating population. Here, we describe an adaptation of a test developed by Manly (1995, Ecology, 76, 1109-1115), which uses the observed association data as a basis for a computer-generated randomization. The observed pattern of association is tested against a randomly created one while retaining important features of the original data, for example group size and sighting frequency. We applied this new method to test four data sets of associations from two populations of Hector's dolphin, Cephalorhynchus hectori, using the Half-Weight Index (HWI) as an example of a measure of association. The test demonstrated that populations with similar median HWI values showed clear differences in association patterns, that is, some were associating nonrandomly whereas others were not. These results highlight the benefits of using this new testing method in order to validate the analysis of association indices. Copyright 1998 The Association for the Study of Animal Behaviour.
关联指数最初是为描述物种共现情况而开发的，但越来越多地被用于衡量个体之间的关联。然而，尚未有已发表的统计方法能让人检验观察到的关联指数值与随机关联种群的指数值之间的差异程度。在此，我们描述了对曼利（1995年，《生态学》，76卷，1109 - 1115页）开发的一种检验方法的改编，该方法将观察到的关联数据用作计算机生成随机化的基础。将观察到的关联模式与随机创建的模式进行检验，同时保留原始数据的重要特征，例如群体大小和目击频率。我们以半权重指数（HWI）作为关联度量的一个例子，应用这种新方法对来自赫氏矮海豚（Cephalorhynchus hectori）两个种群的四个关联数据集进行检验。该检验表明，具有相似中位数HWI值的种群在关联模式上存在明显差异，也就是说，一些种群是非随机关联的，而另一些则不是。这些结果凸显了使用这种新检验方法来验证关联指数分析的益处。版权所有1998年动物行为研究协会。
