Donor aid statistics? Comparative effectiveness of large vs small orgs?

That donor aid is mismanaged gets a decent amount of press. Does anyone know of any legit statistics on how much of the money donated actually reaches those intended vs gets lost along the way? I am having a hard time finding evidence and determining how big of a problem this really is.

Secondly, I expect large organizations in general to be less effective compared to smaller more localized organizations. I also expect this would be hard to measure, and that it is the subject of debate. Can you refer me to a legit publication / article that either proves or disproves this?

I don’t tend to thank people individually for answers, but please know I appreciate every one of them :)