A recent article argues that investing in local arts programs leads to economic revitalization in struggling neighborhoods. It claims cities that allocate funds for arts initiatives witness a boost in local business revenues and increased tourism. While supporters of the article point to several case studies illustrating this phenomenon, critics argue that correlation does not imply causation. The critics assert that other factors, such as improved infrastructure or increased population density, could be the true drivers behind these economic improvements.

In evaluating this argument, which of the following, if true, would most seriously weaken the critics' position?