Duplicates: 1 copy of 90814 observations and 0 surplus

[Carolin Luisa]

Hello, I need help turning a dataset into panel data. I am using a dataset from OECD https://stats.oecd.org/Index.aspx?Da...=AIR_EMISSIONS and look only at the observations for Sulphur. Using the comman "duplicates report" I get 1 copy of 90814 observations and 0 surplus. So now I can't turn them into panel data because of duplicates. But if I drop the duplicates only observations from one country remains. What can I do to fix this problem?

[Nick Cox]

That's good news -- so far as it goes.

If there is one copy of each observation, it is ipso facto unique,

Consider this silly example. An identifier created as such evokes the summary report.

. clear

. set obs 10
number of observations (_N) was 0, now 10

. gen id = _n

. duplicates report id

Duplicates in terms of id

--------------------------------------
   copies | observations       surplus
----------+---------------------------
        1 |           10             0
--------------------------------------

. list id

     +----+
     | id |
     |----|
  1. |  1 |
  2. |  2 |
  3. |  3 |
  4. |  4 |
  5. |  5 |
     |----|
  6. |  6 |
  7. |  7 |
  8. |  8 |
  9. |  9 |
 10. | 10 |
     +----+

.

The issue with that dataset is just that you need a reshape to get where you need to be. I downloaded the csv after which this worked for me -- although look at the file to see the metadata you might need.

replace pol = subinstr(pol, "PM2-5", "PM25", . )

egen which = concat(pol var unitcode), p(_)

drop pol* var* unit* flag* power* ref*

reshape wide value, i(cou year) j(which) string

rename value* * 

egen id = group(cou), label 

xtset id year