A tire company wants to determine if tires made with a new type of tread will last longer than tires made with
the original type of tread. The company has access to
24 different vehicles. Each vehicle will receive four tires
with the new tread and four with the original tread. The
position, front or back, will be randomly determined for
a pair of each type of tread. For example, a vehicle will
have the new type of tread on the front tires and the
original tread on the back
tires. After six months, the
pairs of unused tires will be used with the position
switched on the car. The vehicles will be driven for six
more months. At the end of one year, the depths of the
remaining tread will be measured for each tire and the
average differences between the new and original tread
types will be determined. The average differences will
then be used to determine if the new tread does last
longer.
Is this a matched pairs design?
A) Yes, the company used 24 different vehicles.
B) Yes, both types of tread were randomly assigned to each vehicles.
C) No, the vehicles were not put into groups of two.
D) No, the tires with the different types of tread were not randomly assigned to each vehicle.