st: bar graph test scores, pre and post

[Nicholas Gebbia <nicholasjgebbia@gmail.com>]

Hey!

I have a graphing question that may be a simple fix, but I’m having a
hard time figuring it out. I’m making bar graphs of student quiz
scores, for pre- and post-quizzes. Ideally, I would like the graph to
show mean score for each question, with the pre-quiz and post-quiz
means side-by-side for each question – and then I’d do the same for
the mean total score at the end as well.

Right now, the closest I’ve gotten is...

graph bar (mean) q1 q2 q3, over(post)

(less customizing specifications). This gives the mean score for each
question, with pre-quiz means clustered together followed by post-quiz
means also clustered, or,

q1pre – q2pre – q3pre – (break) – q1post – q2post – q3post.

What I want is,

q1pre – q1post – (break) – q2pre – q2post – (break) – q3pre – q3post.

I suspect the reason I’ve had such a hard time working with the over()
command is that it requires a categorical variable, whereas the
Question variables don’t fit that mold. Any commands I’m missing, or
any way I could manipulate the variable definitions to get what I
want? (Right now, my observations are all doubles with a dummy "post"
identifying the pre- or post-survey, e.g. two observations have ID
number 32, one of which is labeled "post", and one of which is labeled
"pre"; I could easily merge observations if that would help the
coding.)

Any help is much appreciated.
Thanks!

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