Testing for spatial correlation in nonstationary binary data, with application to aberrant crypt foci in colon carcinogenesis
Testing for spatial correlation in nonstationary binary data, with application to aberrant crypt foci in colon carcinogenesis
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DOI：
10.1111/j.0006-341x.2003.00088.x
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发表时间：
2003-12-01
期刊：
影响因子：
1.9
通讯作者：
Carroll, RJ
中科院分区：
文献类型：
--
作者：
Apanasovich, TV;Sheather, S;Carroll, RJ
在一项了解结肠癌发生的实验中，所有动物都暴露在一种致癌物质中，其中一半的动物也暴露在辐射中。在空间上，我们测量了所谓的异常隐窝病灶(ACF)的存在，即已知为结肠癌发展前驱的形态改变的结肠隐窝。令人感兴趣的生物学问题是这些ACF的位置是否在空间上相关：如果是，这表明致癌物质和辐射对结肠的损害是局部的。从统计上讲，数据在规则网格上采用二元结果的形式(对应于ACF的存在)。我们开发了基于MATERN和条件自回归(CAR)相关模型的记分型方法来检验此类数据中的空间相关性，同时考虑到非平稳性。由于分数类型测试的技术特性，我们还开发了该方法的健壮版本。将这些方法与连续结果的Moran检验的推广进行了比较，并通过模拟表明这些方法具有增加功率的潜力。当应用于我们的数据时，这些方法表明空间相关性的存在，从而表明损伤的局部性。
In an experiment to understand colon carcinogenesis, all animals were exposed to a carcinogen, with half the animals also being exposed to radiation. Spatially, we measured the existence of what are referred to as aberrant crypt foci (ACF), namely, morphologically changed colonic crypts that are known to be precursors of colon cancer development. The biological question of interest is whether the locations of these ACFs are spatially correlated: if so, this indicates that damage to the colon due to carcinogens and radiation is localized. Statistically, the data take the form of binary outcomes (corresponding to the existence of an ACF) on a regular grid. We develop score-type methods based upon the Matern and conditionally autoregressive (CAR) correlation models to test for the spatial correlation in such data, while allowing for nonstationarity. Because of a technical peculiarity of the score-type test, we also develop robust versions of the method. The methods are compared to a generalization of Moran's test for continuous outcomes, and are shown via simulation to have the potential for increased power. When applied to our data, the methods indicate the existence of spatial correlation, and hence indicate localization of damage.