What is that the system to defend the body by producing hormones, including thymosin, which t-cells to mature, and adrenaline, which the body to fight or run away from large external threats?

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.