如图,按ID对数据进行分类,生成新变量time1,取值为time=1时的age值,以此类推生成time2,time3等,最后生成这张图
如何通过stata实现呢
可以使用Stata的egen命令来实现按ID对数据进行分类,并生成新变量。具体操作如下:
sort ID
egen time1 = mean(cond(time==1, age, .)), by(ID)
egen time2 = mean(cond(time==2, age, .)), by(ID)
egen time3 = mean(cond(time==3, age, .)), by(ID)
graph twoway (scatter time1 ID) (scatter time2 ID) (scatter time3 ID)
完整代码如下:
sort ID
egen time1 = mean(cond(time==1, age, .)), by(ID)
egen time2 = mean(cond(time==2, age, .)), by(ID)
egen time3 = mean(cond(time==3, age, .)), by(ID)
graph twoway (scatter time1 ID) (scatter time2 ID) (scatter time3 ID)