My guess is that there will be a chance of crowd-out and for givers who are at their hard limits on their charitable giving the crowd-out will be 100%. I would not expect a very good rule of thumb to exist.
That said, there may be things you can do to minimize it (just off the top of my head):
Make your request unique so that it doesn’t bring to mind other places people are donating to
Make a case that giving to your cause can make other giving more effective
Make your request at times where people get fewer requests (e.g., not around the holidays)
One time requests tied to a specific event like a natural disaster are more easily absorbed without offsetting reductions
Giving small perks people might value a lot might help them slot this giving separately from other forms of giving and thus not feel the need to offset it
A very good question, and a nice and thoughtful answer.
I think this has been an ongoing debate on donation matching and giving multipliers I’d just add that this is one of the reasons why neglectedness is my favorite (and neglected) ITN metric—it’s hard to crowd-out resources for neglected causes.
My guess is that there will be a chance of crowd-out and for givers who are at their hard limits on their charitable giving the crowd-out will be 100%. I would not expect a very good rule of thumb to exist.
That said, there may be things you can do to minimize it (just off the top of my head):
Make your request unique so that it doesn’t bring to mind other places people are donating to
Make a case that giving to your cause can make other giving more effective
Make your request at times where people get fewer requests (e.g., not around the holidays)
One time requests tied to a specific event like a natural disaster are more easily absorbed without offsetting reductions
Giving small perks people might value a lot might help them slot this giving separately from other forms of giving and thus not feel the need to offset it
A very good question, and a nice and thoughtful answer.
I think this has been an ongoing debate on donation matching and giving multipliers
I’d just add that this is one of the reasons why neglectedness is my favorite (and neglected) ITN metric—it’s hard to crowd-out resources for neglected causes.