An interesting observation made by the firefighters was that some parts of the forest seemed to escape the flames. the crown fire would drop down into a ground fire in these areas, and then jump back up into the canopy as the fire burned into adjacent areas. they observed that many of these areas had previously been thinned, which means that some of the trees were cut down and hauled away to be used as timber. in other areas, thinned forests burned with as much severity as the unthinned forest. your objective is to design an observational study to answer the question: what was the determining factor for areas that escaped the worst impacts of the fire, compared to areas that were severely burned?

According to the previous observational study it is possible to notice that thinning determined in great way the rate of trees that survived the fire.

Explanation:

In general the trees that had been previously cut, were the ones that presented more resistance to the fire, while the trees that had not been thinned were the ones that were severely affected in the spreading conflagration. Reason why in comparison of these two samples, it would be possible to conclude that previously cutting down trees can survive better to the spreading fire.

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.

your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.