Hi Suzana,

in SPSS times are internally stored as seconds from midnight. So it is fairly easy to round up to 30 minutes=1800 seconds

*example data set.

DATA LIST /ID 1 time 3-7 (TIME).

BEGIN DATA

1 10:11

2 11:01

3 12:45

4 01:04

5 00:01

6 23:55

END DATA.

DATASET NAME set1.

COMPUTE test=RND((time)/1800)*1800.

EXE.

*to get it in hh:mm format use FORMATS.

FORMATS test (TIME5).

cheers.

Many Thanks :)