Assignment #7 - 2019

This assignment uses some data (data is here) that is similar to data I analyzed for the Animal Health and Performance Program (AHPP) over at the Vet School. The AHPP is the program that oversees the EcoDogs, and also does a lot of research into the performance of sporting dogs.

In this study, the AHPP was interested in how training and conditioning influenced the ability of detection dogs to perform strenuous tasks. The performance ability of the dogs was measured using heart-rate as an index of condition. The basic description of their experimental design follows. Eight dogs were each subject to two conditioning 'treatments'. All dogs were first kept in a kennel with minimal exercise for 3 months. After the dogs had been completely de-conditioned, a round of measurements were taken ('baseline'). Following the initial round of measurements at the baseline treatment, each dog was conditioned via strenuous exercise for 2 months, after which a second round of measurements were taken ('pc' - post conditioning). During the baseline and pc phases, each dog had to perform tasks on each of 5 consecutive days. On each day, measurements of each dog's heart rate were taken at 7 times ('events') in the following order: before any exercise ('pre'), following a series of sprints ('post sprint'), following a series of jumping exercises ('post jumps'), following a run up and down an a-frame ('post a frame'), following a steady jog ('post run'), 10 minutes after completion of the exercises ('post 10 minutes'), and 20 minutes after completion of the exercises ('post 20 minutes'). 

Your job is to determine if there are significant effects of conditioning, day, or event on heart rate (save yourself a serious headache and don't bother looking at interactions). For those factors that are significant, you'll need to determine which groups within that factor are different from each other (don't use Tukey, use changes in model structure to accomplish this task). For this assignment, I want you to treat 'Day' as a continuous variable. You should be able to do this with a single model (although you'll have to relevel it for questions 4 and 5).

In your assignment, you should write sentences that report:

1. The difference between baseline and post-conditioning phases (i.e., does conditioning the dogs affect their heart rate)

2. The effect of day on heart rate. (Day should be a continuous variable)

3. The difference between heart rate at 10 post exercise and 20 minutes post exercise

4. The difference between heart rate after the 'Jumps' event and the 'Run' event

5. The difference between heart rate before exercise ('Pre') and after the 'A frame' event.

6. What is the variation (standard deviation) in heart rate due to 'dog'?

7. Finally, don't you think it's interesting that there is no significant affect of conditioning on heart rate? Why might you have not found a result? How could you change your analyses to better elucidate the effects of conditioning on heart rate?

Hint: this experiment is essentially a temporal version of the 'split-plot' design we discussed in class (water plots, nested within fertilizer plots, nested within cow plots, nested within fields). You'll need to figure out exactly what is nested within what for the analysis. Report differences among treatments using the standard sentences.