It's not exactly like there is some secret lab, built into the side of a mountain somewhere cranking out data on it, but some research has attempted to discern the differences between a persuasive solicitation letter and one that makes a do-not-pass-go trip to the junk mail pile. A 2009 study argues that effective direct-mail solicitation establishes an authoritative, erudite tone rather than telling a sad story or making a good argument.
"Persuasion in Fundraising Letters: An Interdisciplinary Study," published 2009 in Nonprofit and Voluntary Sector Quarterly, documents an experiment in which 41 graduate students and alumni at Indiana University-Purdue Indianapolis each received a hypothetical $100 to award between sets of two fake solicitation letters from fake universities. The content of the letters was based on 245 actual, direct mail solicitations from the Indiana Center for Intercultural Communication’s (ICIC) Fundraising Corpus, altered slightly to employ different styles of persuasion.
Some of the fake letters appeal to the emotions of the recipient; others concentrate on old fashioned, fact-based rhetoric; still a third set relies on the credentials of the person and institution requesting the funds. Respondents tended to give the most fake money to the fake letters in the third category.
Researchers in disciplines such as applied psychology, linguistics and communications have been interested in solicitation letters since at least the early 1980s. These letters provide an opportunity to study the mechanics of persuasion in its natural habitat. But while universities and other types of fundraisers surely monitor what works and what does not in their solicitations, the "research findings are proprietary and, if they are shared at all," they do not undergo any type of rigorous peer-review.
Nevertheless, those responsible for the 2009 study readily admit that their case is anything but airtight. Maybe the participants favored the second of the two letters they read in succession because it was fresher in their mind when they went to assign the $100; maybe the fact that participants had to choose one of the two letters, while in reality "the vast majority of direct-mail solicitations letter are thrown out unopened" skewed the findings.
But why study snail mail at all in the 21st century? It turns out that "nonprofit organizations continue to use direct-mail in some way," even in the Internet era. As recently as 2000, research has shown that paper letters in paper envelopes still draw in more first-time donors than any other single type of solicitation. The study's authors also believe that what holds true on paper may also translate effectively to Internet solicitations.