Question

Vehicle brake pads can either be metallic or non-metallic. A brake pad manufacturer is going to conduct an experiment to compare stopping distance across brake pad types. It’s also known that the size of the vehicle (e.g., small, medium, large) affects stopping distance, but previous studies have found that vehicle model (sedan, SUV, coupe) does not seems to be associated with stopping distance.

Which of the following variables should the manufacturer use as a blocking variable in the experiment?

• A. Vehicle model

• B. Brake pad type

• C. Vehicle size

• D. Stopping distance

Answer 1

Blocking is a technique for dealing with nuisance factors.

A nuisance factor is a factor that has some effect on the response, but is of no interest to the experimenter; however, the variability it transmits to the response needs to be minimized or explained

Here we have to compare the stopping distance for different type of brake pad. So stopping distance is our variable of interest. We have to eliminate the effect of size of vehicle on the stopping distance.so this is our blocking variable.