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Censored Data
known more precisely than it is. Of course, wherever the data provide an exact numeric
value, as in the case of Patient 24 who is known to have survived for 218 days, that
exact numeric value is used.
Recoding the Data
The data file needs to be recoded before Amos reads it. The next figure shows a portion
of the dataset after recoding. (This complete dataset is in the file transplant-b.sav.)
Every uncensored observation appears in the new data file just the way it did in the
original data file. Censored values, however, are coded differently. For example,
Patient 25’s survival time, which is known only to be greater than 1,799, is coded as
> 1799 in the new data file. (Spaces in a string like > 1799 are optional.) The square root
of survival time is known to be greater than 42.415, so the timesqr column of the data
file contains > 42.415 for Patient 25. For data file formats (like SPSS Statistics) that
make a distinction between numeric and string variables, time and timesqr need to be
coded as string variables.
Analyzing the Data
To specify the data file in Amos Graphics:
E From the menus, choose File > Data Files.