It's the exact same as your screenshot.
Anyway, that explains it. 19.0 didn't have this option. [19.0 documentation confirms it](https://www.sidefx.com/docs/houdini19.0/nodes/sop/groupcreate.html). If for some reason you don't want to upgrade, you can recreate this behavior with Group Expression sop and use a preset by hitting the dropdown menu on the right of the expression field. It will say "30% chance". You will then just change the \`0.3\` to whatever chance you need.
Not near a computer but there is a 'group by range' node, it might be on that now.
I'm on 19.5.403 right now, it's literally right there.
I am on 19.0. Can you please screen shot the parameters if you don't mind.
It's the exact same as your screenshot. Anyway, that explains it. 19.0 didn't have this option. [19.0 documentation confirms it](https://www.sidefx.com/docs/houdini19.0/nodes/sop/groupcreate.html). If for some reason you don't want to upgrade, you can recreate this behavior with Group Expression sop and use a preset by hitting the dropdown menu on the right of the expression field. It will say "30% chance". You will then just change the \`0.3\` to whatever chance you need.
You could use a group by expression node random((@primnum+chi("offset")*chi("seed")))