data merge: r(459);

[Seyed Mahmoud Hosseinniakani]

Hi,
I have two panel data-set and what to merge the two data set. I use the following code but I receive the error "r(459); variable firmid does not uniquely identify observations in the master data". I double-checked for duplicate observation and no duplicate observation reported. I would be grateful if you help regarding the error.

Code: megre dataset1 with dataset2
merge 1:1 firmid using dataset2
or
merge m:1 firmid using dataset2

Kindly,
Mahmoud

[Rich Goldstein]

how did you check this? try:

sort firmid
count if firmid==firmid[_n-1]

do this in each data set

you could also use the -duplicates command-; see

help duplicates

or try

duplicates report firmid

again, do this in each file

[Seyed Mahmoud Hosseinniakani]

Rich:
Both data set are in panel data. I thought is I should use the following code for checking the duplicate. As you see in follow, when I run the code1 the result shows no duplicate. While, when I run code 2 (your suggested code) which do not contain -year- it shows different results. I am not sure how to fix this.


Code 1:

. duplicates report firmid year

Duplicates in terms of firmid year

--------------------------------------
copies | observations surplus
----------+---------------------------
1 | 2208 0
--------------------------------------

.

Code 2:

. sort firmid

. count if firmid==firmid[_n-1]
1,840

.
. duplicates report firmid

Duplicates in terms of firmid

--------------------------------------
copies | observations surplus
----------+---------------------------
6 | 2208 1840
--------------------------------------

[Rich Goldstein]

there are two obvious possibilities but there may be others if you supply more info about what is going on: (1) merge on both firmid and year; (2) use either -joinby- or -cross-

[Seyed Mahmoud Hosseinniakani]

I am not following you perhaps. I tried cross and joinby but it didn't work well. I have been using -merge- much time. This is the first time I am facing this problem. Could you please let me know how to apply -joinby- and -Cross- in my case. I could not well understand the example from Stata help.

Thanks in advance!

[Clyde Schechter]

I think you should try the first suggestion that Rich Goldstein made in #4:

merge 1:1 firmid year using dataset2

When you want to merge panel data, you usually need to specify both the panel variable and the time variable.

[Seyed Mahmoud Hosseinniakani]

Thank you Rich and Clyde. As you suggested, I tried to merge with both firmid and year thus it works well.

Kindly,
Mahmoud