STATA 11 for Windows SAMPLE SESSION - Food Security Group ...

Stata 11 Sample Session Section 2 – Restructuring Data Files – Table Lookup & Aggregation
The drop command
(see the previous merge), so we don't need to sort it again.
Stata will reuse the _merge variable again with the next
join we do, so we should drop this variable first since we
no longer need it. The command to delete a variable is
called drop
The Stata command is:
drop _merge
Now we are ready for the next join:
1. From the Data menu select Combine datasets,
then select Form all pairwise combinations
within groups
The joinby - form all pairwise combinations within
groups dialog box opens.
2. To fill in the box labeled Filename of dataset
on disk: click on the Browse button, Select the
filename calories.dta and click on Open.
3. In the box labeled Join observations by
groups formed from specific variables, select
prod only
4. Click on the “Options” tab.
5. Under “Unmatched Observations”, select
Include from data in memory
This option will keep cases in the original
data set that do not have a match in the
lookup data set.
6. Click on the copy button, switch to the do-file
editor, paste the command, delete the directory
reference, switch back to the dialog box and
click on Ok
7. Add comments to the do-file.
The Stata command is:
joinby prod using "calories.dta", unmatched ( master )
_merge(_merge)
The new working data file produced by the merge now
contains the needed calorie variable, calories, but check
to make sure. Maize grain (PROD=47) should have 3590
calories per kilogram in the calories variable. We can
browse the data and/or we can use the list command
again.
The Stata command is:
list prod calories if prod==47
Also check the _merge variable to see how the merge was
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