Just an idea.
What do you think if a campaign appears in which 16 people (or 100) will participate?
But only 1 user will receive the payment weekly. That is, by means of raffle, a winner will be determined who will receive the entire amount of the campaign’s weekly budget.
I wouldn't want to participate in such a campaign, too. This is too much gamble for my taste and statistics could make you have to wait for a really long period until you win such a raffle (potential for quite some frustration; something I'd rather not associate with a campaign).
Then there's indeed what Turbartuluk mentions how to account for the posting quality and quantity of each campaign participant. I see no easy and fair solution to treat everybody based on their contribution during the campaign.
I'm not very good at statistics but if you actually do such a campaign, what do you think of the following additional rules?
- a raffle winner takes it all but then has to leave the campaign forever
- the freed spot by the last raffle winner is of course replenished by only one new participant
- total number of participants of the campaign is constant with a fair and not too high upper limit
Just some ideas I had while thinking over such a campaign proposal... (I still wouldn't want to participate even with my suggestions)