How does the amount of vegetation affect the way a sand dune forms

Sand dunes are formed from wind movement. There needs to be a large amount of loose sand in an area with hardly any vegetation, enough wind to move grains of sand and some kind of obstacle to make the blowing sand lose its momentum and settle in a new place.

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.