Question

Treatment for Cocaine Addiction

Cocaine addiction is very hard to break. Even among addicts trying hard to break the addiction, relapse is common. (A relapse is when a person trying to break out of the addiction fails and uses cocaine again.) A study is conducted to investigate the effectiveness of two drugs, desipramine and lithium, in the treatment of cocaine addiction. The subjects in the six-week study were cocaine addicts seeking treatment. The 72 subjects were randomly assigned to one of three groups (desipramine, lithium, or a placebo, with 24 subjects in each group) and the study was double-blind. Now we are able to consider all three groups together and test whether relapse rate differs by drug. Ten of the subjects taking desipramine relapsed, 18 of those taking lithium relapsed, and 20 of those taking the placebo relapsed.

(a) Create a two-way table from the information given.

	Relapse	No relapse	Total
Desipramine	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement
Lithium	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement
Placebo	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement
Total	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement	Enter your answer in accordance to item (a) of the question statement

(b) Find the expected counts.

	Relapse	No relapse
Desipramine	Enter your answer in accordance to item (b) of the question statement	Enter your answer in accordance to item (b) of the question statement
Lithium	Enter your answer in accordance to item (b) of the question statement	Enter your answer in accordance to item (b) of the question statement
Placebo	Enter your answer in accordance to item (b) of the question statement	Enter your answer in accordance to item (b) of the question statement

Is it appropriate to analyze the data with a chi-square test? Choose the answer from the menu in accordance to item (b) of the question statement                                                          YesNo

(c) If it is appropriate to use a chi-square test, complete the test, give the chi-square statistic, the p-value, and an informative conclusion.

Round your answer for the chi-square statistic to one decimal place, and your answer for the p-value to three decimal places.

chi-square statistic = Enter your answer in accordance to item (c) of the question statement

p-value = Enter your answer in accordance to item (c) of the question statement


Conclusion: Choose the answer from the menu in accordance to item (c) of the question statement                                                          Do not rejectReject H0.

Does the test indicate an association between the type of drug and relapse rate?

Choose the answer from the menu in accordance to item (c) of the question statement                                                          YesNo

(d) If the results are significant, which drug is most effective?

Choose the answer from the menu in accordance to item (d) of the question statement                                                          LithiumPlaceboDesipramine

Can we conclude that the choice of treatment drug causes a change in the likelihood of a relapse?

Choose the answer from the menu in accordance to item (d) of the question statement                                                          YesNo

Answer 1

A)Two way table

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

B)Expected frequency

	Relapse	No relapse
Desipramine	16	8
Lithium	16	8
Placebo	16	8

c)The chi-square statistic is 10.5.

The p-value is .005248
The result is significant at p < .05.

Hence we reject H₀

Yes there is an association between type of drug and relapse rate

D)Since the result is significant, the drug Placebo is more effective since the proportion of Placebo in curing is the highest .

E)The choice of type of drug causes a change in the likelihood of relapse

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