Some marketers at Harley Corner believe that considering the "customized food option" is a significant factor in increasing monthly purchases. However, others argue that the impact of customized food options on frequency of purchases depends on whether customers are enrolled in loyalty programs. Specifically, only loyalty program members find customized food options attractive, due to its high impact on their loyalty score, compared to non$-$members.

$-$ Please develop an appropriate model to test this idea and interpret the results.