You have been hired by the Canadian bicycle team to help them train for the Tour de France. The head trainer recently read an article, which presents the results of a study about the effects of the consumption of chocolate (dark chocolate and white chocolate) on a number of important outcome variables during cycling. These outcome variables included: oxygen consumption (ml/kg/min), heart rate (bpm), blood lactate (BLa), blood pressure (mmHg), and an all-out bicycle sprint performance (meters).
The experimental setup consisted of a randomized design where the various outcome variables of n = 9 male participants was measured in two trials after participants consumed either 40 mg of dark chocolate or 40 mg of white chocolate, each for two weeks. Prior to receiving the first treatment, each participant underwent baseline measurements on the outcome variables.
The trainer was specifically interested in the results for the all-out sprint performance which measured the distance traveled (in meters) for a two-minute time trial. He would like to know how the regular consumption of chocolate affects the total distance covered during an all-out sprint and if the type of chocolate consumed matters.
Some of these results are presented in the table below.
Distance Covered (in meters = m) during Time Trial* Note: n = 9 for each condition
|Baseline||White Chocolate||Dark Chocolate|
|Std dev (m)||171||248||158|
|Hypothesis p-value||Ho: = 1367 Ha: > 1367||0.319||0.001|
Dark Chocolate: 95% Confidence Interval for the population average change in total distance covered (dark chocolate over baseline) is 165 m to 314 m
Dark versus White Chocolate: 95% Confidence Interval for the population average change in total distance covered (dark chocolate over white chocolate) is 82 m to 292 m
The trainer knows you have some statistics background and wants your help on understanding and interpreting these results. Based on the results from the article, write a memorandum to the trainer addressing his questions and explaining what these statistics results show.
Although this sample size is small, you can consider it a reasonable one for this type of study, and can thus focus on interpreting the results. Of the hypothesis testing methods (parametric or non-parametric) shown in this class, which do you think was most appropriate for this study. Be sure to comment about the two provided confidence intervals, including an interpretation of both confidence intervals, and an explanation of the meaning of the confidence level in context. Finally, include in your memorandum your recommendation, with stats rationale, for or against inclusion of chocolate (and if inclusion, which type of chocolate) in the athletes’ diet.
Data is from: Patel, R. K.; Brouner, J.; Spendiff, O. Journal of the International Society of Sports Nutrition. 2015 12:47. Link: https://jissn.biomedcentral.com/articles/10.1186/s12970-015-0106-7
A Few Notes for Completing the Assignment
Some Items to keep in mind:
When your memorandum is read by the head trainer with minimal statistical literacy, who is trying to understand these results.
Since you are explaining this to your client, the head trainer, you should take care to carefully edit and proofread your memorandum.
Your memorandum should be between 350-500 words (excluding header, footer, citations). In case you aren’t sure what memorandum (or, “memo”) format should look like: https://owl.purdue.edu/owl/subject_specific_writing/professional_technical_writing/memos/parts_of_a_memo.html
You may need to include citations and sources when discussing the data from this study. When referencing the data, you can use the following source: R. K.; Brouner, J.; Spendiff, O. Journal of the International Society of Sports Nutrition. 2015 12:47. If you use additional sources in your response, be sure to include in-text citations and a references section and use APA format.