This question is about the "in" of Stata.

You must refer to http://www.stata.com/help.cgi?in.

They said "in at the end of a command means that the command is to use only the observations specified."

In your case, "list urbrur in 1/10" is to display the data of urbrur from 1(first data) to 10(tenth data).

And "_n" is the order of data. So if your first data is 123 and your tenth data 100,

list urbrur if _n=1

then display 123

list urbrur if _n=10

then display 100. So I think the correct command is "list urbrur if _n=<10".

Also "_N" is the maximum order of data. So if you have ten data in the above case, "_N" means 10.

I hope you get the answer and enjoy Stata's world.

in 1/10  表示第1到第10个样本

_n 是一个表示样本需要的标识，比如有100个观察值，那么对应的 _n 值就是 1,2,3..., 100.

把陈峰的书先看看，然后在学习别的。stata关键是一些最基础的命令。下面的链接你可以下载许多stata的书

https://bbs.pinggu.org/thread-188730-1-1.html