Silverman E, Kot M
School of Natural Resources and Environment, University of Michigan, Ann Arbor 48109-1115, USA.
Bull Math Biol. 2000 Mar;62(2):351-75. doi: 10.1006/bulm.1999.0159.
This paper introduces a simple stochastic model for waterfowl movement. After outlining the properties of the model, we focus on parameter estimation. We compare three standard least squares estimation procedures with maximum likelihood (ML) estimates using Monte Carlo simulations. For our model, little is gained by incorporating information about the covariance structure of the process into least squares estimation. In fact, misspecifying the covariance produces worse estimates than ignoring heteroscedasticity and autocorrelation. We also develop a modified least squares procedure that performs as well as ML. We then apply the five estimators to field data and show that differences in the statistical properties of the estimators can greatly affect our interpretation of the data. We conclude by highlighting the effects of density on per capita movement rates.
本文介绍了一种用于水禽运动的简单随机模型。在概述了该模型的属性之后,我们将重点放在参数估计上。我们使用蒙特卡罗模拟将三种标准最小二乘估计程序与最大似然(ML)估计进行比较。对于我们的模型,将过程协方差结构的信息纳入最小二乘估计并没有什么好处。事实上,协方差指定错误会比忽略异方差和自相关产生更差的估计。我们还开发了一种性能与ML相当的修正最小二乘程序。然后,我们将这五种估计方法应用于实地数据,并表明估计方法统计属性的差异会极大地影响我们对数据的解释。我们通过强调密度对人均运动速率的影响来得出结论。