方法以全国1999年B超法检查34549例8,9,10岁儿童甲状腺容积的数据为基础，利用累计频数法、聚类分析法作分组、分类分析、划分所求得目标界限并用实际数据作合理性检验。
Methods Based on data composed of 34 549 cases of thyroid volume in children aged 8 , 9 and 10 years , we used the methods of cumulative frequencies and cluster analysis for the study of our data in detail .
累计频数