The management of a large retail company reported a significant increase in sales after running a series of promotional campaigns over the last year. The company's CEO claimed that the success of the campaigns was directly linked to the increased consumer interest generated by social media advertising. However, the marketing director argued that while social media played a role, the company's overall product quality improvements were more influential in boosting sales.

Given this context, which of the following, if true, would most seriously weaken the CEO's claim that social media advertising was the primary factor for the increase in sales?