But the research also shows that tip size is affected by the size of the dining party (larger groups tip more), the method of payment (credit cards yield higher percentages than checks or cash), and by the amount of alcohol consumed (not surprisingly).

FORBES: Tips for Influencing the Size of Tips

After filling out a long questionnaire with a substantial amount of personal information, I was prompted to select a package and enter a payment method.

FORBES: Financial Aid or Financial Fraud?