I just went on a rule of thirds when I simplified it.
If one needs to simplify the thirds, then deny can have a zero value.
0 - 5 = deny
6 - 10 = trial
11 - 15 = full
1. category = 3
2. category = 2
3. category = 0
4. category = 1
5. category = 0
End result of six, Trial member.
Of course the numbers for each category can vary, for instance to make it harder to become a full member the trial numbers could be 6 - 12, or even 8 - 12, which would also make it easier to be denied. This of course would be based for an individual vote. Simply take total numbers and divide accordingly.
Once the established voting system is in place, changing it would be someone higher up on the food chain.