Most retail stores have implemented self-checkout systems to enhance checkout services and ultimately improve customer satisfaction. Long lines at checkout counters can influence a customer's decision to shop at a particular retailer (Chain Store Age, 2008). While Juntti (2014) argued that self-checkout systems are costly and do not necessarily reduce transaction times or the number of customers in line, Morimura and Nishioka (2016) suggested that they are effective in reducing perceived waiting times. However, it has not yet been quantitatively verified whether self-checkouts actually decrease customer waiting times.

This study addresses two key research questions: 1) Do self-checkouts truly reduce customer waiting time? and 2) How can we determine the optimal ratio of self-checkout counters to regular cashier lanes? To investigate these questions, we developed a simulation model using Arena simulation software to analyze waiting-related performance metrics such as customer waiting time and the number of customers in line at both self-checkout and regular cashier lanes. An extensive simulation study is conducted, taking into account factors such as arrival rates and the number of cashiers and self-checkout lanes, using data collected from a grocery store.