Answer:
a)
The explanatory variable is the variable that is being manipulated or changed in the study, while the response variable is the outcome that is being measured or observed. For example, in a study on the effects of a new medication on blood pressure, the explanatory variable would be the medication (whether the participant received the new medication or a placebo) and the response variable would be the blood pressure of the participant.
b)
A well-designed experiment should control for confounding variables, which are variables other than the explanatory variable that could influence the response variable. One way to control for confounding variables is through randomization, where participants are randomly assigned to the different treatment groups (e.g., medication vs. placebo). This helps ensure that any confounding variables are equally distributed among the groups, reducing their potential impact on the results.
c)
If researchers were surprised to discover that the placebo group showed more improvement than the treatment group, it could mean that the treatment had no effect, or that the placebo had a positive effect, such as a placebo effect. This highlights the importance of including a control group in experiments to help distinguish between the effects of the treatment and any potential placebo effects.