* SPSS data sources.

* (example from SAS Language Reference:  Concepts).

* In-line data.

data list list
  /PatientID (a4) Week1 Week8 Week16.
compute loss = week1 - week16.
begin data
2477 195 177 163
2431 220 213 198
2456 173 166 155
2412 135 125 116
end data.

descriptives variables=week1 to loss.

* From a file.
data list list file="y:\spss\data\input\weight.dat"
  /PatientID (a4) Week1 Week8 Week16.
compute loss8 = week1 - week8.
compute loss16 = week1 - week16.

descriptives variables=loss8 loss16.

* Using GET DATA (from a file only).
* Note:  I find documentation for this command to be incomplete.
get data
  /type=txt
  /file="y:\spss\data\input\weight.dat"
  /delimiters=" "  /* although data is DELIMITED by default, there is no default DELIMITER */
  /variables = PatientID a Week1 f Week8 f Week16 f. 
/* " = " before variable list REQUIRED for delimited data */

compute loss8 = week1 - week8.
compute loss16 = week1 - week16.
compute avgloss = mean(loss8, loss16).
descriptives variables = avgloss.