Question

Does talking on a cell phone make people react slower when driving? Sixty volunteers agree to have their reaction times tested in a driving simulator. Thirty of the drivers were randomly assigned to talk on the phone during the simulation, while the other drivers do not talk on the phone. During the simulation, a surprise event occurred which required the subjects to step on the brake. The time it took them to react is recorded. The mean response time of those talking on the phone was 4.3 seconds. The mean response time of those not talking on a cell phone was 2.9 seconds.

Describe how you would randomly assign the participants to each treatment. (Use a random number generator, random number table, or other method.)

Why is random assignment important for this experiment?
A. It make sure we select subjects at random from the population of drivers.
B. It groups drivers with similar skills and ages together.
C. It distributes variables we cannot control across the different treatment groups.

(45 points)

Answer 1

How to Randomly Assign Participants:

1. Create a list of all the participants (in this case, the 60 volunteers).
2. Use a random number generator, a random number table, or a similar method to assign each participant a random number.
3. Sort the list of participants based on these random numbers.
4. Divide the sorted list into two equal groups: one group to talk on the phone during the simulation, and the other not to talk on the phone.

Why Random Assignment is Important:

C. It distributes variables we cannot control across the different treatment groups.