Question

1. a study was conducted to determine if taking a daily dose of aspirin reduces chance of catching the common cold. this study was conducted using 550 volunteers who were not already on an aspirin regimen. the subjects were randomly assigned to one of two groups: a treatment group who received a low dose of aspirin daily, or a control group who received a placebo. the subjects were unaware of what group they were in. at the end of the study, the subjects were asked to meet with a doctor to discuss if they had any symptoms pertaining to the common cold.

a) what would be the advantage of having this study be double blind?
b) describe what the “placebo effect” would look like in this experiment.

Explanation:

a) In a double - blind study, neither the participants (the volunteers) nor the researchers (the doctors assessing the symptoms) know who is in the treatment group (receiving aspirin) and who is in the control group (receiving placebo). This reduces bias. Participants' expectations (if they knew they were in the treatment group, they might report fewer symptoms due to belief in the drug) and researchers' expectations (if they knew which group a participant was in, they might interpret symptoms differently) are eliminated.
b) The placebo effect occurs when participants in the control group (receiving the placebo) report fewer cold symptoms. This is because their belief that they are receiving a treatment (even though it is a placebo) can influence their perception of their health. For example, if a significant number of control - group participants think they are taking aspirin (due to the study design), their psychological state might make them feel that they have fewer cold symptoms than they actually would without any treatment - like belief.

Answer:

a) Reduces both participant and researcher bias.
b) Control - group participants report fewer cold symptoms due to belief in treatment.