Question

Does alcohol consumption cause increased cravings for cigarettes? Research at Purdue University suggests this is so (see CNN.com web site article "Researchers Find Link Between Cigarette Cravings and Alcohol," dated June 13,1997 ). In an experiment, 60 heavy smokers and moderate drinkers were divided into two groups. One group drank vodka tonics and the other group drank virgin tonics (tonic water alone), but all subjects were told they were drinking vodka tonics. The researchers then measured the level of nicotine cravings (by monitoring heart rate, skin conductance, etc.). Those who had consumed the vodka tonics had \(35 \%\) more cravings than those who did not. Assuming that the assignment of subjects to the treatment (vodka) and control groups was made at random, do you think there are any confounding factors that would make conclusions based on this experiment questionable?

Short answer

There are potential confounding factors that could potentially affect the performance of this experiment, including variables related to the time of day, environment, or pre-existing knowledge of the participants, along with other factors related to the participants' smoking and drinking habits, mental state, diet, and general health. While the experimental structure is sound, these potential confounding factors merit consideration when interpreting the results.

Step-by-step solution

Understanding the experiment design

Firstly, the experiment must be examined to assess its structure. Participants were divided into two groups: a treatment group that drank vodka tonics and a control group that drank virgin tonics. Both groups were told they were drinking alcoholic beverages. This raises initial questions about the placebo effect, but it also eliminates it as a confounding factor because both groups believed they were consuming alcohol, so any observed differences should be due to actual alcohol consumption.

Identifying potential confounding factors

Despite the well-designed structure of the experiment, a few potential confounding factors could distort the results. It is critical to consider factors such as the participants' previous drinking and smoking habits, their mental state during the experiment (stress levels, for instance), the participants' diet and general health, and the accuracy and consistency of the craving measurements.

Critically evaluating the potential for confounding factors

While the experiment seems well controlled, a critical evaluation might reveal the following: the time of day when the experiment was conducted, the environment in which the experiment was conducted, and the knowledge about nicotine cravings and alcohol that participants had before participating in the study. These are all possible confounding factors. Although the subjects were randomly assigned to the treatment and control groups, thereby reducing individual biases, the aforementioned factors could introduce systemic bias into the experiment.