A recent analysis of various grocery store chains indicated that those implementing a rewards program tend to attract more customers compared to those that do not. The analyst concluded that such programs directly lead to increased customer loyalty, which becomes evident in higher sales figures.
However, some have argued that increased customer traffic may not stem solely from rewards programs. They suggest that external factors, such as seasonal promotions or local events, might also play a significant role.
Which of the following, if true, would most strengthen the analyst's conclusion that rewards programs drive customer loyalty?