Offer Three Options When Persuading

I recently dined at a restaurant in Southern California that, on the receipt, included in small font what 15% of the bill was, as a guide for tipping. I've never seen this done before. It was helpful.

But they're leaving money on the table. If I ran a restaurant, on each tab I'd include a "Tip Guide" suggestion with three percentages:

15%
17%
20%

If most of your patrons usually tip 15% (the standard in restaurants in the U.S.), by making 15% the lowest of three, more will choose 17%. Persuasion research shows that people tend to choose the middle of three options and are heavily influenced by relativity -- ie, what a number/option is relative to other numbers/options.

Naturally, this is a concept not limited to restaurant tabs. In any kind of negotiation, framing your desired outcome in the context of other choices is key.