Risk pooling reduces inventory variability by aggregating demand across multiple locations or products. This strategy lowers safety stock requirements while maintaining service levels. It is widely used in inventory planning to counter variability due to uncertain demand patterns across the supply chain.
"Risk pooling is most effective in reducing inventory and managing variability because demand uncertainties across regions can offset each other when aggregated."
- APICS Dictionary, 16th edition; also referenced in MRP material on inventory strategies

Enterprise resource planning (ERP) systems are software platforms that help organizations manage and integrate the essential parts of their businesses, such as finance, supply chain, operations, human resources, and more. ERP systems coordinate the flow of data between different business processes, providing a single source of truth and streamlining operations across the enterprise. ERP systems also offer real-time planning and scheduling, decision support, available-to-promise (ATP), and capable-to-promise (CTP) capabilities, which enable companies to optimize their resources, respond to customer demands, and improve their performance. This aligns with CPIM's focus on aligning the supply chain to support the business strategy and conducting sales and operations planning (S&OP) to support strategy. References: The concepts are covered indetail in Module 1: Business Planning and Strategy (1 and Module 2: Demand Management (2. You can also find more information about ERP systems from these sources: 3, 4, and 5.

The time spent in queue by a specific manufacturing job is determined by the priority of the order. Priority is the relative importance or urgency of an order compared to other orders in the system. Priority can be assigned based on various criteria, such as due date, customer preference, profitability, or first-come-first- served. Priority determines the order in which jobs are processed at each workstation and affects the waiting time and flow time of each job. Higher priority jobs have shorter waiting times and lower priority jobs have longer waiting times. Priority can be used as a tool to manage the trade-offs between customer service, capacity utilization, and inventory levels. References:
* Managing Supply Chain Operations, Chapter 7: Scheduling and Sequencing, Section 7.2: Priority Rules
* CPIM Exam Content Manual, Module 6: Detailed Schedules, Section 6.2: Scheduling and Sequencing, Subsection 6.2.2: Priority Rules

Safety factor is a multiplier that is applied to the standard deviation of demand to determine the safety stock level. Safety factor remains constant while maintaining the same customer service level, as it reflects the desired probability of not stocking out. The higher the safety factor, the higher the customer service level, and vice versa. The other factors do not remain constant while maintaining the same customer service level.
Reorder point (ROP) is the inventory level that triggers a replenishment order. ROP increases with increasing forecast error, as more safety stock is needed to cover the demand uncertainty. Safety stock is the inventory that is carried to protect against forecast errors and demand fluctuations. Safety stock increases with increasing forecast error, as more buffer is needed to avoid stockouts. Inventory investment is the total value of the inventory that is held in the system. Inventory investment increases with increasing forecast error, as more inventory is required to maintain the same customer service level. References: Safety Factor | APICS Dictionary Term of the Day, APICS CPIM 8 Planning and Inventory Management | ASCM