Keep it Short
They say brevity is the soul of wit. Austin Frakt says it's also the soul of persuasion. To prove it, he points us to Tim Harford, who summarizes an experiment in which various versions of a letter were sent to people who might qualify for a refund on a product they bought:
[Four] tweaks had substantial effects: first, cutting a paragraph of waffle that had helped to bury the message about the refund; second, pointing out that a five-minute phone call would suffice to make a claim; third, sending a follow-up letter. And twice as large as any of these effects was adding a couple of bullet points in bold at the top with the key message: you may deserve a refund; if so, call us.
Of course, we already knew this, right? It's why journal abstracts exist. It's why blogs exist. It's why haiku exists. Come on! We're busy people around here.
On the other hand, it doesn't explain the appeal of those endless, rambling, conspiracy theory laden letters that people like Glenn Beck and Ron Paul send out. What's the deal with those, anyway?