I'll briefly describe the setup of the file and syntax.
The way the file is organized is one row per measurement.
Subno Group Task Angle RT
1 1 1 30 1260
1 1 1 30 1410
1 1 1 90 1700
There are two groups, both having 16 subjects. So I numbered the
subjectno from 1 to 32, subjects 1..16 adhering to group 1, and
subjects 17..32 adhering to group 2. All subjects have repeated
observations (10 or so) for each factor of each task. There are two
tasks (labeled 1 and 2), and for each of these tasks, there is an
Angle specified, which has 7 levels (0..180 in 30 degrees steps). The
dependent variable is RT (reaction time, measured in msec).
Task is a fixed factor, since it can only have two levels, task1 or
task2. Same applies to Group. Angle on the other hand, is a random
factor, since the levels we chose for angle are not the only levels
that one can choose, it's just some levels of this ordinal variable.
And subject is also a random factor, since subjects are drawn at
random from both groups. (so is there a problem here already, when
subject is a random factor, and group a fixed factor, in building a
nested term of the two?)
I would like to test for possible group differences, group*task
interactions, and group*task*angle interactions.
The syntax for the GLM is the following:
rt BY angle group task subno
/CRITERIA = CIN(95) MXITER(100) MXSTEP(5) SCORING(1)
SINGULAR(0.000000000001) HCONVERGE(0, ABSOLUTE) LCONVERGE(0,
/FIXED = task | SSTYPE(3)
/METHOD = REML
/RANDOM = subno(group) angle | COVTYPE(ID) .
Thanks again for your help!
> Hi Floris. If you post your syntax (for the GLM), maybe I,
> or someone else, can spot the problem. And remind us of the
> format of your data file--i.e., is it one row per
> measurement (LONG file) with variables to code for Subject,
> and all the other variables?