Cosella is conducting an experiment where she assesses how quickly teenagers can run a 100-meter race after consuming specific amounts of caffeine. She divides her sample up into three groups. Group 1 receives a glass of water (zero caffeine). Group 2 receives the equivalent of the caffeine in one cup of coffee. Group 3 receives the equivalent of two cups of coffee. Each participant is then timed as they run the course. In this study, the independent variable is
A) the previous running experience of each participant.
B) the teenagers who are being studied.
C) the time it takes to run the 100-meter race.
D) the amount of caffeine being ingested.

Question

Quizplus · Accepted Answer

The independent variable is the variable that is being manipulated by the researcher, in this case, the amount of caffeine being ingested. Therefore, the correct answer is D. Options A and B are not independent variables as they do not vary systematically or are not manipulated. Option C is the dependent variable as it is the variable being measured or observed to assess the effect of the independent variable.

Cosella Is Conducting an Experiment Where She Assesses How Quickly