能明白 这句话的意思吗？ repeated time values within pane

翻译出来就知道那里错了。

刚学stata的面板操作时好象很多人都会遇到这个问题，而且不知道怎么解决？记得当初我也是这样的。

[此贴子已经被作者于2007-10-13 11:00:45编辑过]

* input the data

clear

input id year
1      1990
1      1990
1      1991
2      1990
2      1991
2      1991
end

* xtset , but stata report error!

xtset id year

repeated time values within panel
r(451);

* because, there are repeated year obs

duplicates report

Duplicates in terms of id year

--------------------------------------
   copies | observations       surplus
----------+---------------------------
        1 |            2             0
        2 |            4             2
--------------------------------------

* solution: drop duplicates

duplicates drop id year, force

Duplicates in terms of id year

(2 observations deleted)

* Now,xtset is OK

xtset id year
       panel variable:  id (strongly balanced)
        time variable:  year, 1990 to 1991

*-----Appdex--------The do files----------------

clear
input id year
1      1990
1      1990
1      1991
2      1990
2      1991
2      1991
end

cap xtset id year
duplicates report id year
duplicates drop id year, force
xtset id year