Science Buddies: "Ask an Expert"

Pls HELP ASAP! I'm so confuse! I've already done my experiment. I had 5 people (healthy individuals, did not drink any type of caffeine for 1 week before the experiment). 3 people drank the Monster energy drink (480 ml) & 2 drank just water (480 ml). My mom who is a nurse took their baseline blood pressure and heart rate before drinking The Monster and water. Then they drank the fluids. They rested for 45 minutes (no walking or running allowed). My mom took their b.p. and hr again, I recorded all of these of course. I saw the increase of heart rate not the b. pressure to the 3 monster drinkers, not the water drinkers. So I made these 5 people do very active exercise for 1 hour in the gym. As soon as they finished, my mom took their bp and hr again. After that, they waited 30 more minutes of normal activities (not exercise) and my mom took their bp and hr again. .....so pls correct me if I'm wrong, is my INDEPENDENT variable the monster drink only? CONSTANT variable is same AMOUNT of drinks in milliliter, same time of activities, same time blood pressure and heart rate taken? DEPENDENT is the blood pressure and heart rate? CONTROl would be my water drinkers only??? What about my Monster drinkers? Which ones are they?.......... ***** I'm also stuck how to make graphs for my systolic and diastolic blood pressure and heart rate. Is that means I should have like 3 graphs? Pls help me. Other people are telling me different ways to do it...that's why I need an expert to help me :0( thank you very much. By the way I'm in 6th grade now.

Hello,

Please take a look at this Science Buddies article about scientific variables:

https://www.sciencebuddies.org/science- ... bles.shtml

Here is another useful page:

http://www.ncsu.edu/labwrite/po/independentvar.htm

"In some cases, you may not be able to manipulate the independent variable. It may be something that is already there and is fixed, something you would like to evaluate with respect to how it affects something else, the dependent variable like color, kind, time." It looks like you did not vary the amount of Monster that the participants drank; I assume that they drank it all so this remains a fixed 480mL.

Independent Variable = "What I change" (in this case, it appears that would be your Monster drinkers)
Dependent variable = "What I observe" (in this case, it's your blood pressure and heart rate)
Control = your water drinkers only

Yes, your controlled variable looks correct (amount of drinks, type and time of activities, same time BP and HR)

I would do 3 different graphs since you will have entirely different units.

Please read up about systolic and diastolic BP here:

http://en.wikipedia.org/wiki/Blood_pressure

I hope that helps.

Hi medavv,

You have a very interesting project! I am not sure why you chose not to have the water drinkers do the exercise part of the experiment. Keep in mind that a science fair judge may ask you this, so you will need to be ready with an explanation. Since the water group was your CONTROL group, most scientists would have had that group do the exercise part as well. Since you are already finished with your experiment, we can work with what you have!

For the resting measurements, the water group is your control. You will want to compare resting heart rate and blood pressure for the water (control) group and the Monster (experimental) group at rest. It is quite interesting that you saw an increase in heart rate and not blood pressure!

For the exercise measurements, the Monster group will serve as their own control. You will want to compare the resting heart rate and blood pressure measurements for the Monster group to the post-exercise measurements for the same group. Be careful what you conclude from this, since you do not have the exercise measurements for the water group.

As for your graphs, it would be okay to graph systolic and diastolic blood pressure on the same graph, and heart rate on a separate graph. When doctors and nurses read blood pressure, it is usually reported as systolic/diastolic (i.e., 120/80). So it's fine to graph both numbers on the same graph, to give your audience an easier time comparing them.

I hope that helps. Let me know if anything I said doesn't make sense or you need more help with your graphs.

Good luck!
Heather