This isn't a study, but as far as the science of philanthropy goes I know of no one better to look to than GiveWell and they did write a blog post about it: htt

This isn't a study, but as far as the science of philanthropy goes I know of no one better to look to than GiveWell and they did write a blog post about it: https://blog.givewell.org/2011/12/20/give-now-or-give-later/ https://blog.givewell.org/2011/12/20/give-now-or-give-later/