Is a duration chart possible?
 

In Numbers I can calculate the duration between two dates.
If I copy such a column and paste into OGS it comes up blank.
Is it somehow possible to plot duration?

Hmm, as long as your duration column in numbers is in a numerical format, OmniGraphSketcher should paste it just fine. Would it be possible to attach a copy of your Numbers document to a post, or email [email]omnigraphsketcher@omnigroup.com[/email], so we an figure out what's going wrong?

If you have two date columns in Numbers, and make a third column that subtracts them, you get a column full of things like 1d, 2d, 3d, etc. OGS doesn't know what to do with that...

Like palmer said it's not just numerical data. Numbers has a special duration format which you get when you subtract two dates. You can manually set how you want it presented. E.g. "2d 5h" or just "2d" etc.

I did some digging on the Apple forums. Apparently only one out of all the graph types support the time duration format. I believe it's called the "scatter" chart.

I got a recommendation to convert the duration to days with a function here:
[URL="https://discussions.apple.com/thread/3978666?tstart=0"]https://discussions.apple.com/thread/3978666?tstart=0[/URL]

It would be nice if OmniGraphSketcher fully supported duration out of the box though.

I'll send you an email with a .numbers file in it too.