[Excerpt] The connection between service quality and tip sizes is tenuous at best, as shown by an analysis of 14 studies that examined the relationship between service and tips. This meta-analysis of the studies sought to statistically combine 24 correlations between tipping and service. While the studies taken together found that, indeed, tips increased with the perceived quality of service, the relationship was weak enough to raise doubts about the use of tips to motivate servers, measure server performance, or identify dissatisfied customers.
Lynn, M. (2001). Restaurant tipping and service quality: A tenuous relationship [Electronic version]. Cornell Hotel and Restaurant Administration Quarterly, 42(1), 14-20. Retrieved [insert date], from Cornell University, School of Hospitality Administration site: http://scholarship.sha.cornell.edu/articles/113/