Question

Patients who are addicted to cocaine are sometimes using the drug to combat depression. As such, sometimes addicts are given antidepressant medications to prevent relapse. A three-year study compared the effects of two such medications, lithium and desipramine, along with a placebo for 72 cocaine users wishing to break the habit. The patients were put into 3 groups of 24, and given 1 of the 3 treatments at random. This two-way table illustrates the results.

Treatment Relapse No relapse Total
Desipramine 10 14 24
Lithium 18 6 24
Placebo 20 4 24
Total 48 24 72


Give a conditional relative frequency for relapse among patients who took lithium.

A. 18/72 = 25%
B. 27/72 = 33.33%
C. 18/24 = 75%
D. 48/72 = 66.67%

Answer 1

The answer is 18/24

Answer 2

Option C, 18/24 = 75%

Explanation:

Patients who were addicted to cocaine were divided into 3 groups of 24.

Each group was treated with three different drugs. One group of 24 patients were put on Lithium for treatment out of 24 patients who relapsed were 18.

So conditional relative frequency for relapse among patients who took Lithium would be :

Relative frequency of patients = (patients relapsed) / (total number of patients)

Relative frequency =
`(18)/(24)` = 75%

Option C, 18/24 = 75% would be the answer.