stata no panel variable set, use tsset

Question

how to deal with it ?this is the help from stata.

[P] error . . . . . . . . . . . . . . . . . . . . . . . . Return code 198
invalid syntax;
__________ invalid;
range invalid;
__________ invalid obs no;
invalid filename;
__________ invalid varname;
__________ invalid name;
multiple by's not allowed;
__________ found where number expected;
on or off required;
All items in this list indicate invalid syntax. These errors are
often, but not always, due to typographical errors. Stata attempts
to provide you with as much information as it can. Review the
syntax diagram for the designated command.
In giving the message "invalid syntax", Stata is not very helpful.
Errors in specifying expressions often result in this message.
what is the error?waiting on line. thank you!
顺便问一下，处理面板数据的时候,tsset怎么用啊？每一次都说是时间重复，可是webuse grunfeld就可以用，为什么？谢谢！！

Answer 1

意思是说没有面板数据变量
在这之前可以把你导入的普通数据转变为面板数据格式后才可以用tsset或者xtset定义面板数据变量

webuse grunfeld就可以用是因为这个文件是stata公司已经整理好格式后放在网络共享你自己下载后定义面板数据变量后就可以使用啦

Answer 2

运行下面命令后再tsset就可以了
duplicates drop, force