There have been a few studies conducted in the area of Supply Chain Management with respect to the impact of batch sizes on the bullwhip effect in the two-tier Supply Chain. This research differs in three ways from other studies: i) a little research has been done to study the impact of batch size on the bullwhip effect (Disney et al. 2003; Hussain & Darke, 2011). Therefore, this research is going to fulfill this gap in academics. (ii) in this research, a real time data of the rice industry has been collected and two case studies have been analyzed iii) the APIOBPCS Supply Chain model for the first time has been implemented in the rice industry of Pakistan- the only focus of the current research. In academia, a few studies have been conducted in the context of Supply Chain Management with reference to Pakistan; consequently, there are a lot of gaps which need to be researched upon. The present research has quite substantially fulfilled these gaps. It also opens new research doorsfor the future researchers who have a passion to venture into a research in the areas which have not been touched upon.