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We need help with two questions.

Posted: Sun Jan 06, 2013 3:38 pm
by Reese812
My son is performing an experiment on What is harder on the heart going up the stairs or down.

We tested going up two flights of stairs then down. We tested going up one flight of stairs and down. I think that gives us two independent variables and we should only test going up and down 2 flights of stairs. What do you think?

The second question we had was about the amount of data. If we test 5 family members going up and down 2 flights of stairs once each. Is that enough data or should he test us again a second time and get an average heart rate.

Thank you for your help.

Re: We need help with two questions.

Posted: Sun Jan 06, 2013 6:00 pm
by rbeckers7920
Question 1:
Two independent variables is plenty given the project question and purpose. Your independent variable is the direction of movement on the stairs, 1. Up (2 flights) 2. Down (2 flights) and your Control should be a resting heart rate (which can be thought of as no direction or movement on the stairs.) The Control/resting heart rate gives you a clearer idea of the differences in your results. Your results (heart rate values) will be considered your dependent variables.

Question 2:
It is generally a good idea to get an average for each individual. This is because averages can protect against a random event while testing that may otherwise skew your data (can be seen or unseen by the researcher). You can take an average of two trials, or three trials, it is up to you. Generally three is a solid and common number of trials, but it is not always necessary.

To clarify :
So, yes, your two independent variables (2 flights up and 2 flights down)and a control with multiple trials per participant will be enough data without needing to collect data for up one flight then down. And yes, multiple trials will give you a more accurate trend when you begin to look at all of your data.

I really hope this helps.


Re: We need help with two questions.

Posted: Sun Jan 06, 2013 6:07 pm
by dcnick96
Hello, and welcome to Science Buddies. An interesting project!

Let me ask a couple of questions about your test setup first.
1. How are you measuring "harder on the heart?" Pulse rate at the end of the exercise or something else? Are you just reporting the heart rate, or are you comparing the heart rate to the subject's resting heart rate?
2. Are the test subjects taking a break between going up the stairs and going down? They should. Otherwise, whichever is done second (up or down) could be affected by what is done first (up or down). For example, if the subjects climb the stairs first, they should wait until their heart rate returns to normal resting heart rate before going down the stairs.

Now for your questions.
1. Since your title includes, "2 flights of stairs," it is best to stick with just testing two flights of stairs. Also, I don't think there will be a significant difference in measurements between 1 and 2 flights of stairs.
2. Is the age and general health the same across all of the family members? If the family members include ages 10, 30, and 60 (for example), age could be more of a factor than the exercise. This (and other differences between subjects) can be mitigated by reporting a percent increase in heart rate from resting heart rate. (which is why I was asking the question above as to how you are going to measure).

For example, say the resting heart rate of a subject is 60 (60 beats per minute). After climbing two flights of stairs, say the heart rate is 80. Then the percentage increase in heart rate is (80-60)/60 = 33% increase.

I hope this helps. Feel free to write back if you have more questions. Good luck!

Re: We need help with two questions.

Posted: Mon Jan 07, 2013 7:03 am
by Reese812
Thank you for your help

This is my first science fair.

What is the best way to graph the results?

I will have a control group for resting heart rate and two trails . Do I use a bar graph with actual results or the averages? Or is it better to use percentage increase in heart rates?


Re: We need help with two questions.

Posted: Mon Jan 07, 2013 6:46 pm
by klhjbh62604
Hello Reese812:

Great questions. As a third grader, I think the best option at this time would be a bar graph. ... ysis.shtml

I have provided a link to guide you through the process. Please let us know if you have any specific questions while graphing your data. You seem to be on the right track.


Re: We need help with two questions.

Posted: Mon Jan 07, 2013 10:12 pm
by dcnick96
Excellent advice from all of the mentors. If the math is not too difficult, I recommend reporting percentage increase in heart rate. Calculate this for each person and for each trial, and then calculate the average percentage increase. There are so many differences between people that you cannot control in an experiment. Calculating percent increase helps minimize these differences.

I agree that a bar graph is best to post the results.

Good luck with your first science fair. You are asking excellent questions. I know you will do well!