ARCHIVED: In SPSS, why were the results of my merge with MATCH FILES scrambled?
If the results of your merge using the MATCH FILES
command in SPSS are scrambled, follow the example below to fix your
data. If you wish to use SPSS graphical interface to fix the problem,
see SPSS graphical interface below.
The MATCH FILES
command in SPSS merges two data sets to
add or update variables. Without a /BY
or
/TABLE
subcommand, the command sometimes produces odd
results by simply putting two data sets together. The problem becomes
worse when the index variable is not a unique identification variable.
Consider the following data sets and the MATCH FILES
command:
ID V1 V2 ID V3 V4 C:\spss\DATA1.sav 1 1 1 c:\spss\DATA2.sav 1 5 5 1 2 2 2 6 6 2 3 3 2 4 4 MATCH FILES /FILE='c:\spss\DATA1.sav' /FILE='c:\spss\DATA2.sav' /BY ID. EXECUTE.
Since ID
, the index variable, has duplicate cases, SPSS gets
confused and gives you the warning message, "Warning # 5132 Duplicate key
in a file...", producing the following result. Notice that when SPSS found
a duplicate index, it automatically set the variable from DATA2
as missing and then went on to the next unique case.
ID V1 V2 V3 V4 1 1 1 5 5 1 2 2 . . 2 3 3 6 6 2 4 4 . .
To avoid this, use the /TABLE
subcommand to tell SPSS that one
file will be used as a lookup table for the other data set. SPSS will then
look through the file you defined with the /TABLE
subcommand
and use it to match data to each field duplicated in the other file,
for example:
MATCH FILES /FILE='c:\spss\DATA1.sav' /TABLE='c:\spss\DATA2.sav' /BY ID. EXECUTE.
The command with /TABLE
will produce the following data set:
ID V1 V2 V3 V4 1 1 1 5 5 1 2 2 5 5 2 3 3 6 6 2 4 4 6 6
SPSS graphical interface
To merge data using SPSS graphical interface:
- Open the data file
Data1.sav
. - From the menu, select and then .
- Select the file to merge (e.g.,
Data2.sav
), and then click . - In the "Add variables" dialog box, select
This will produce the same results as the example using the
MATCH FILES
command with the/TABLE
option above. It is important to sort both of the data files by key variable(s) before you merge them. and check . Under "Key Variables:", select . Click
.
If you have questions about using statistical and mathematical software at Indiana University, contact the UITS Research Applications and Deep Learning team.
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Last modified on 2023-05-09 14:37:15.