Okubo T
Environ Health Perspect. 1979 Oct;32:75-81. doi: 10.1289/ehp.793275.
The grid square method as used in Japan has been standardized by the government, by use of the lines of the earth's latitude and longitude. The basic unit covers an area of approximately one square kilometer. An evaluation of this method is focused on the geographical distribution of cancer mortality in the city of Tokyo over a period of six years. The results indicated that for stomach and lung cancers, there was a very clear geographical distribution. High stomach cancer areas were similar for both males and females, and by comparing data with census data, it was evident that the blue-collar areas showed high mortality. High lung cancer areas were also similar for both males and females, but the distribution was opposite to that of stomach cancer, i.e., the higher mortality was observed in white-collar areas. Because the basic area unit of one square kilometer was too small for statistical analysis of geographical distribution, the moving average of nine grid squares as well as a "combined grid square method" based on population density was used. By this study a number of advantages of the grid square method as opposed to methods employing existing government boundaries became evident. The boundary lines do not move with political expediencies. X-Y coordinates can be easily defined for statistical analyses by computer, facilitating computer mapping, calculating the center of distribution, determination of the contour lines, and the estimation of values in places which lie between sampling stations.
日本所采用的方格网法已由政府通过利用地球经纬线进行了标准化。基本单元覆盖面积约为一平方公里。对该方法的一项评估聚焦于东京市六年期间癌症死亡率的地理分布情况。结果表明，对于胃癌和肺癌，存在非常明显的地理分布。男性和女性的高胃癌区域相似，并且通过将数据与人口普查数据进行比较，很明显蓝领区域显示出高死亡率。男性和女性的高肺癌区域也相似，但分布与胃癌相反，即白领区域观察到较高的死亡率。由于一平方公里的基本面积单位对于地理分布的统计分析来说太小，因此使用了九个方格的移动平均值以及基于人口密度的“组合方格网法”。通过这项研究，方格网法相对于采用现有政府边界的方法的许多优点变得明显。边界线不会因政治权宜之计而变动。可以轻松定义X - Y坐标以便通过计算机进行统计分析，便于计算机绘图、计算分布中心、确定等高线以及估计采样站之间区域的值。
