Question

9.37 let them eat chocolate. there is some evidence that cocoa has beneficial effects on heart health. to study this, researchers decide to give subjects either a cocoa pill or a placebo daily for a two - year period. measurements of the subjects heart health, based on a questionnaire, before and after the two - year period, are to be compared. 20
a. outline the design of this experiment, using 20 subjects, with 10 assigned to each group
b. here are the names of the 20 subjects. use software or table b at line 129 to carry out the randomization your design requires.
c. do you think this can be run as a double - blind experiment? explain.

Explanation:

Step1: Explain the design

This is a randomized controlled experiment. We randomly assign 10 subjects to the cocoa pill group and 10 to the placebo group.

Step2: Carry out randomization (using Table B at line 129)

Let's assume we use two - digit numbers from Table B. We can label the 20 subjects from 01 - 20 (Abel = 01, Aeffner = 02, Birkel = 03, Bower = 04, DeVore = 05, Fleming = 06, Fritz = 07, Girunas = 08, Kennedy = 09, Lamone = 10, Mani = 11, Mattos = 12, Reichert = 13, Riddle = 14, Sawant = 15, Scannell = 16, Stout = 17, Williams = 18, Wilson = 19, Worhis = 20).

Starting at line 129 of Table B (assuming a standard random number table). Let's say the first 10 non - repeated two - digit numbers between 01 - 20 are selected for the cocoa pill group. For example, if we get 12 (Mattos), 05 (DeVore), 09 (Kennedy), 17 (Stout), 03 (Birkel), 14 (Riddle), 07 (Fritz), 19 (Wilson), 02 (Aeffner), 11 (Mani). Then these 10 subjects are in the cocoa pill group and the remaining 10 (01 (Abel), 04 (Bower), 06 (Fleming), 08 (Girunas), 10 (Lamone), 13 (Reichert), 15 (Sawant), 16 (Scannell), 18 (Williams), 20 (Worhis)) are in the placebo group.

Step3: Analyze double - blind possibility

A double - blind experiment is possible. The subjects do not know whether they are taking the cocoa pill or the placebo (blind for subjects). Also, the researchers who measure the heart health (based on the questionnaire) do not know which group each subject is in (blind for researchers).

Answer:

a. This is a randomized controlled experiment. b. The randomization depends on the actual numbers from the random number table (example groups shown above). c. Yes, it can be run as a double - blind experiment because both subjects and researchers can be kept unaware of the group assignments.