For the following description of​ data, identify Who and What were investigated and the population of interest. A researcher wondered whether drivers treat bicycle riders differently when they wear...

For the following description of​ data, identify Who and What
were investigated and the population of interest.

A researcher wondered whether drivers treat bicycle riders differently when they wear helmets. He rigged his bicycle with an ultrasonic sensor that could measure how close each car was that passed him. He then rode on alternating days with and without a helmet. Of the 4000 times that a car passed​ him, he found that when he wore his​ helmet, motorists passed 3.07 inches closer to​ him, on​ average, than when his head was bare.