Question

You wonder if TV ads are more effective when they are longer or repeated more often

or both. So you design an experiment. You prepare $30$-second and $60$-second ads for a

camera. Your subjects all watch the same TV program, but you assign them at random

to four groups. One group sees the $30$-second ad once during the program; another sees

it three times; the third group sees the $60$-second ad once; and the last group sees the

$60$-second ad three times. You ask all subjects how likely they are to buy the camera.

Which of the following best describes the design of this experiment?

a. This is a randomized block design, but not a matched pairs design.

b. This is a matched pairs design.

c. This is a completely randomized design with one explanatory variable (factor).

d. This is a completely randomized design with two explanatory variables (factors).

e. This is a completely randomized design with four explanatory variables (factors).

Short answer

The correct option is:

d. This is a completely randomized design with two explanatory variables (factors).

Step-by-step solution

Given information

We have been given four options from which we have to select the correct one.

a. This is a randomized block design, but not a matched pairs design.

b. This is a matched pairs design.

c. This is a completely randomized design with one explanatory variable (factor).

d. This is a completely randomized design with two explanatory variables (factors).

e. This is a completely randomized design with four explanatory variables (factors).

Explanation

It is a perfectly randomised design because all individuals were randomly assigned to one of the four groups.This is a completely randomized design with two explanatory variables (factors).