Restaurant customers preferred spending more when classical music is being played in a restaurant, than if pop or no music is being played.

This study is not blocked but treatment assignment was randomized. The sample is comprised of people who decided to go to this restaurant, not of random people taken and exposed to the setting. It is single blinded, as the subjects didn't know what condition they're in, but researchers do.

Participants in this study are customers of this restaurant between February and March 2002, with 393 total restaurant goers. The experimental units analyzed are comprised of the parties of restaurant-goers, with n=141. The sample is approximately equal with regards to male/female ratio.

All conditions were kept constant apart from music choice. Each condition lasted for 6 total nights.

For a multivariate analysis of covariance, a significant difference was found between conditions on participant spending with p=0.007, significant at an alpha of 0.01. Total spending on food was found to differ overall between the three conditions. For all significant dependent variables, classical music gave rise to the greatest spending.

We can derive a causal relationship between music choice and spending for this restaurant, and restaurants like it. The conclusion in the Lam article is justified in its presentation of the results, as it simply reports what was found in the study.