Question

In order to study the effects of caffeine on the resting heart rate, 20 adult volunteers were placed into two groups, and all of their heart rates were recorded. One group was given a caffeine pill, and the second group was given a sugar pill. After one hour, all of their heart rates were recorded again, and the changes in heart rates between the two groups were compared. Complete the sentences to accurately describe the situation.

The explanatory variable of this experiment is _________.

A) Caffeine intake
B) Sugar pill
C) Resting heart rate
D) Placebo effect

The response variable of this experiment is _________.

A) Caffeine pill
B) Sugar pill
C) Changes in heart rates
D) Placebo effect

The placebo was the _________.

A) Caffeine intake
B) Sugar pill
C) Resting heart rate
D) Placebo effect

Answer 1

The explanatory variable in the caffeine study is caffeine intake, the response variable is changes in heart rates, and the placebo is the sugar pill.

Step-by-step explanation:

The explanatory variable of this experiment is A) Caffeine intake. The explanatory variable is the condition that is manipulated by the researchers to observe the effect it has on the response variable, in this case, caffeine intake versus a control substance.

The response variable of this experiment is C) Changes in heart rates. This variable measures the outcome of interest, which the study is attempting to measure or the effect of the explanatory variable.

The placebo was the B) Sugar pill. In a controlled experiment, a placebo is an inert substance given to the control group to mimic the experimental treatment and manage the effects of participant expectation or the placebo effect.