What should be done to ensure a car seat is installed securely?

To ensure a car seat is installed securely, it should not move more than one inch side to side or front to back at the belt path. This guideline is crucial for child passenger safety because excessive movement can indicate that the car seat is not properly anchored, which reduces its effectiveness in a crash. A securely installed car seat minimizes the risk of injury by preventing the car seat from shifting during sudden stops or collisions.

The specified allowance of one inch is a standard measure used by safety experts to assess whether the seat is correctly installed. It ensures that the seat is stable enough to protect the child effectively while still being functional for parents to install and remove when necessary.

In contrast, a car seat that moves freely or has loose straps would not offer adequate protection in the event of a crash. Likewise, while a proper installation angle is important for some car seats, merely stating a 45-degree angle without referring to secure installation does not address the core aspect of this question.