Someone (not me) might want to perform historic or chronological calculations before October 15, 1582 -- for example, life expectancy during the Black Death, 1348 - 1350. To do that in SPSS with its date limitations I suppose one would have to assign an arbitrary zero point to a certain date and work from there. SAS assigns zero to January 1, 1960 but I haven't checked SAS for dates preceding October 15, 1582.
Jason meant 1582, not 1592. However, as the following demo shows, datetime
variables actually store the number of seconds since 14-Oct-1582 00:00:00.
But notice that the minimum valid numeric value is 86400, which is the
number of seconds in one day.
data list list / seconds(f12.0).
begin data
0
86399
86400
86401
86402
86460
172800
end data.
numeric datettimevar (datetime).
compute datettimevar = seconds.
list.
OUTPUT:
seconds datettimevar
>Warning # 1140
>The value to be output under one of the date formats is negative or has a
date
>part of zero. The result has been set to the system-missing value.
0 .
>Warning # 1140
>The value to be output under one of the date formats is negative or has a
date
>part of zero. The result has been set to the system-missing value.
86399 .
86400 15-OCT-1582 00:00:00
86401 15-OCT-1582 00:00:01
86402 15-OCT-1582 00:00:02
86460 15-OCT-1582 00:01:00
172800 16-OCT-1582 00:00:00
Number of cases read: 7 Number of cases listed: 7
Jason Becker wrote:
>
> Indeed, there is something wrong with your understanding. As mentioned
> earlier, though you see the date format as dd-mm-yyyy, SPSS stores the
> information as a number of seconds since 15-10-1592 00:00:00.
Locked
