repeated measure datafile

[Thomas, Dave-2]

 

I have a repeated measure data file as the example given below:

 

ID         Time     Volume

1          1          500

1          2          550

1          3          400

1          4          300

1          5          200

2          1          1000

2          2          1100

3          1          450      

3          2          350

3          3          250

 

If I wanted to make all cases have the same number of time points by
adding missing values (rows) of volume for time points that are missing
for each case - what is the easiest way to accomplish this in SPSS v.16?

 

Thanks in advance for any suggestions.

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[Richard Ristow]

At 02:33 PM 6/6/2008, Thomas, Dave wrote:

>I have a repeated measure data file as the example given below:

|-----------------------------|---------------------------|
|Output Created               |09-JUN-2008 07:38:14       |
|-----------------------------|---------------------------|
ID Time Volume

  1   1     500
  1   2     550
  1   3     400
  1   4     300
  1   5     200
  2   1    1000
  2   2    1100
  3   1     450
  3   2     350
  3   3     250

Number of cases read:  10    Number of cases listed:  10


>If I wanted to make all cases have the same number of time points by
>adding missing values (rows) of volume for time points that are
>missing for each case - what is the easiest way to accomplish this
>in SPSS v.16?

For any version of SPSS having CASESTOVARS/VARSTOCASES, you can use
"long-wide-long" code, as below. The awkward point is that the
VARSTOCASES has to be hand-coded to match the set of variables
transposed ('Time' and 'Volume', in your example), and the maximum
number of instances observed in the input (5, in the example).
Generating a VARSTOCASES to undo the effect of a preceding
CASESTOVARS would be an interesting Python exercise, and very useful;
but I don't know that anyone's done it. (I mean to, but haven't
tackled it yet.)


SORT CASES BY ID .
CASESTOVARS
  /ID = ID
  /GROUPBY = VARIABLE .

Cases to Variables
|-----------------------------|---------------------------|
|Output Created               |09-JUN-2008 07:39:21       |
|-----------------------------|---------------------------|

Processing Statistics
|---------------|---|
|Cases In       |10 |
|Cases Out      |3  |
|---------------|---|
|Cases In/Cases |3.3|
|Out            |   |
|---------------|---|
|Variables In   |3  |
|Variables Out  |11 |
|---------------|---|
|Index Values   |5  |
|---------------|---|


VARSTOCASES  /MAKE Time FROM Time.1 Time.2 Time.3 Time.4 Time.5
  /MAKE Volume FROM Volume.1 Volume.2 Volume.3 Volume.4 Volume.5
  /KEEP =  ID
  /NULL = KEEP.

Variables to Cases
|-----------------------------|---------------------------|
|Output Created               |09-JUN-2008 07:41:40       |
|-----------------------------|---------------------------|
Generated Variables
|------|------|
|Name  |Label |
|------|------|
|Time  |<none>|
|Volume|<none>|
|------|------|

LIST.

List
|-----------------------------|---------------------------|
|Output Created               |09-JUN-2008 07:41:40       |
|-----------------------------|---------------------------|
ID Time Volume

  1   1     500
  1   2     550
  1   3     400
  1   4     300
  1   5     200
  2   1    1000
  2   2    1100
  2   .       .
  2   .       .
  2   .       .
  3   1     450
  3   2     350
  3   3     250
  3   .       .
  3   .       .

Number of cases read:  15    Number of cases listed:  15
=============================
APPENDIX: Test data, and code
=============================
DATA LIST LIST /
     ID         Time     Volume
    (N2,        F2,      F5).
BEGIN DATA
     1          1          500
     1          2          550
     1          3          400
     1          4          300
     1          5          200
     2          1          1000
     2          2          1100
     3          1          450
     3          2          350
     3          3          250
END DATA.
LIST.


SORT CASES BY ID .
CASESTOVARS
  /ID = ID
  /GROUPBY = VARIABLE .
LIST.

VARSTOCASES  /MAKE Time FROM Time.1 Time.2 Time.3 Time.4 Time.5
  /MAKE Volume FROM Volume.1 Volume.2 Volume.3 Volume.4 Volume.5
  /KEEP =  ID
  /NULL = KEEP.
LIST.

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