Question

Scientists at a major pharmaceutical firm investigated the effectiveness of an herbal compound to treat the common cold. They exposed each subject to a cold virus, then gave him or her either the herbal compound or a sugar solution known to have no effect on colds. Several days later they assessed the patient's condition, using a cold severity scale ranging from 0 to \(5 .\) They found no evidence of benefits associated with the compound.

Short answer

The herbal compound showed no significant benefit over a placebo for treating the common cold.

Step-by-step solution

Identify the Experiment Type

The pharmaceutical firm conducted an experiment to test the effectiveness of an herbal compound on the common cold. This classifies as a controlled experiment because subjects were given either the herbal compound or a sugar solution (placebo).

Determine the Variables

The independent variable is the treatment given to subjects (herbal compound or placebo). The dependent variable is the patients' condition measured by the cold severity scale ranging from 0 to 5.

Evaluate the Experiment's Conclusion

The conclusion of the experiment was that there was no evidence of benefits associated with the herbal compound. This likely means that the severity scores for patients receiving the herbal compound were not significantly different from those receiving the placebo.

Key concepts

Controlled Experiment

A controlled experiment is a scientific method designed to minimize the effects of variables other than the independent variable. This approach ensures that the outcomes are directly attributable to the variable being tested. In the given experiment concerning the herbal compound's effectiveness on the common cold, a controlled experiment was chosen.
Here’s why this is ideal:

• Subjects are divided into groups: one receives the herbal compound, and the other receives a placebo, a sugar solution known to have no effect on colds.
• By using a placebo, researchers can control for the placebo effect, where subjects might feel better simply because they believe they are receiving treatment, not because of the treatment itself.
• A controlled setting helps to ensure any differences in outcomes can be more accurately attributed to the herbal compound rather than other external factors.

In essence, controlled experiments are crucial in substantiating the cause-and-effect relationship by limiting external variables that could impact the results.

Independent Variable

The independent variable in an experiment is the one that is manipulated or changed to observe its effect on the dependent variable. It’s the factor that researchers are interested in studying. For the experiment on the common cold treatment, the independent variable is the type of treatment administered to the subjects.
This means:

• Subjects were either given the herbal compound (the factor under study) or a sugar solution (placebo).
• The choice of treatment is crucial as it determines what variable is being tested and how various outcomes are compared.
• Researchers carefully control this variable to ensure that any changes in the dependent variable can be ascribed to it, rather than other factors.

The independent variable is the foundation upon which the experiment is built, allowing for the investigation of its direct impact on the outcome.

Dependent Variable

The dependent variable in an experiment is what researchers measure to assess the effect of the independent variable. It is observed and recorded to determine the experiment's outcomes. In the case of the pharmaceutical firm's study, the dependent variable is the condition of the patients, measured by the cold severity scale.
Here are the details:

• The cold severity scale ranges from 0 to 5, where 0 indicates no symptoms and 5 indicates severe symptoms.
• Researchers assess the effectiveness of the herbal compound by comparing the severity scores between the two groups – those who took the compound and those who took the placebo.
• By keeping the measurement method consistent (using the cold severity scale), reliable data is gathered on how much the independent variable (treatment) affects the outcomes directly.

The dependent variable is crucial as it concretely shows the results of manipulating the independent variable, thereby forming the basis for drawing any conclusions.