Final answer:
In a clinical trial, important considerations including the population, sample, experimental units, explanatory variable, response variable, and treatments are defined to ensure validity and reliability of the results while addressing ethical considerations. Lurking variables need to be identified and controlled, and blinding can be used to minimize biases.
Step-by-step explanation:
When designing a clinical trial, researchers must carefully define the population, which is the entire group under study, and select a representative sample from this population to participate in the trial. The experimental units in a clinical study are the individual participants or subjects. The explanatory variable, also known as the independent variable, is the variable that is manipulated to observe its effect on the response variable, which is the outcome being measured. Treatments refer to the different levels or categories of the explanatory variable applied to experimental units. When selecting participants, it is necessary to consider factors like demographics, health status, and other characteristics to ensure the sample reflects the population.
In the example of a study testing the impact of texting while driving, the groups are those driving without distraction versus those texting. Randomly dividing participants into these two groups ensures that each group is likely to be similar in all respects except for the treatment. However, if the study involves real driving scenarios, ethical considerations prevent putting participants at risk, so simulation would be a safer method. Lurking variables are those not measured in the study that could affect the results, such as the skill level of the driver or road conditions. To minimize biases associated with expectancy or subjectivity, researchers can employ blinding, where participants, those administering the treatments, or those measuring the outcomes are kept from knowing who is receiving which treatment.