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The researchers were interested in understanding the effects of illicit drugs on brain functioning. They recruited participants from local Narcotics Anonymous support groups. Thirty-eight former drug users participated in the study. Fifteen reported cocaine as their drug of choice, 10 indicated heroin as their drug of choice, and 13 indicated synthetic marijuana as their drug of choice. After providing basic demographic information (sex, age, ethnicity), the participants consented to a PET scan of their brain to assess cerebral blood flow. The cerebral blood flow of participants in the three drug groups was analyzed using a one-way ANOVA. The results indicated cerebral blood flow was not affected by drug use (F(2, 35) = 1.82, p .05). The researchers concluded that drug abuse does not affect cerebral blood flow. These results suggest drugs do not affect the brain as once believed.
Based on the information provided, do you agree with the researchers' conclusion? What changes in the research design would you need to be able to believe that drugs do not affect cerebral blood flow? Fix it!

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The researchers were interested in understanding the effects of illicit drugs on brain functioning. They recruited participants from local Narcotics Anonymous support groups. Thirty-eight former drug users participated in the study. Fifteen reported cocaine as their drug of choice, 10 indicated heroin as their drug of choice, and 13 indicated synthetic marijuana as their drug of choice. After providing basic demographic information (sex, age, ethnicity), the participants consented to a PET scan of their brain to assess cerebral blood flow. The cerebral blood flow of participants in the three drug groups was analyzed using a one-way ANOVA. The results indicated cerebral blood flow was not affected by drug use (F(2, 35) = 1.82, p > .05). The researchers concluded that drug abuse does not affect cerebral blood flow. These results suggest drugs do not affect the brain as once believed.
Based on the information provided, do you agree with the researchers' conclusion? What changes in the research design would you need to be able to believe that drugs do not affect cerebral blood flow? Fix it!

Quizplus · Accepted Answer

The Answer is Experiments are the only research method capable of making cause-and-effect statements. This is because experiments involve the direct manipulation of an independent variable and the measurement of a dependent variable while controlling for other confounding variables (Ref 2-1, 35). Even though the researchers manipulated drug type and measured cerebral blood flow, they cannot say the two are related because there was no control group (Ref 8-1, p. 244). The researchers should add a control group of participants who are not drug users. In doing so, the cerebral blood flow of each drug group can be compared to the control group. An ANOVA can then determine if drug users have different levels of cerebral blood flow compared to "normal" individuals (Ref 9-1, p. 295).

Fix It The Researchers Were Interested in Understanding the Effects of Illicit