Data Analysis is confusing us!

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My daughter's question is "How does jumping affect a horse's heart and respiration rates?" For her experiment she set up a jump course. Test A was riding the course with the poles on the jumps and Test B was riding the same course with no poles on the jumps (so no jump... just riding through the standards). She managed to keep the speed consistent and took the heart and respiration rates immediately following each test. She allowed the horse to cool down for 10 minutes between tests. She wanted to have as many trials as possible without overworking the horse, so she planned to do 3 trials of each test on 3 different horses (have i lost you yet?). Because she ran out of time at the facility where she rode, she completed 3 trials of both tests with one horse but only 2 trials of each test with the other 2 horses.

Our questions are:
1. By using more than one horse did we unintentionally add a 2nd variable, thus messing up our experiment?
2. If that is not a problem, should she only use 2 trials for each horse since she was unable to get 3 for each horse?
3. Should she treat each ride as a separate trial (ending up with 7 trials for each test) or leave each horse with its separate trials?
4. When setting up her graphs, should she have 2 graphs (one with heart rate and one for respiration) and have separate color bars for each horse or each trial? Or should she average the trials together and use one color for heart rate and one for respiration?

I'm sorry if this confusing. I can't think of an easier way to explain it.
Kristi

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Dear Kristi,
This is a long question.
1.No you did not add a 2nd variable by adding horses. This is because your question is to find our how jumping affects horse's heart rate and respiration. By adding another horse you have included more subjects to answer your question. The dependent variable for your experiment is heart rate and respiration rate at rest, and your independent variable is respiration and heart rate after jumps.
2. Yes, she should use 2 trials of each horse as she did the same # of trials with each.
3. Each horse should be with its separate trials.
4.She should have 2 graphs one for heart rate and one for respiration rate. She should have separate color bars one each for respiration and heart rate. She can prove or show that the heart rate decreased or increased or stayed the same for each of the horses and based on those results she would be able to conclude that jumping does increase,decrease the heart rate and respiratory rate for horses.
I hope this is helpful. I f you have any additional questions please let me know.


Jay.