/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 68 Athletes competing in a triathlo... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Athletes competing in a triathlon participated in a study described in the paper "Myoglobinemia and Endurance Exercise" (American Journal of Sports Medicine [1984]: 113-118). The following data on finishing time \(x\) (in hours) and myoglobin level \(y\) (in nanograms per milliliter) were read from a scatterplot in the paper: $$ \begin{array}{rrrrrr} x & 4.90 & 4.70 & 5.35 & 5.22 & 5.20 \\ y & 1590 & 1550 & 1360 & 895 & 865 \\ x & 5.40 & 5.70 & 6.00 & 6.20 & 6.10 \\ y & 905 & 895 & 910 & 700 & 675 \\ x & 5.60 & 5.35 & 5.75 & 5.35 & 6.00 \\ y & 540 & 540 & 440 & 380 & 300 \end{array} $$ a. Obtain the equation of the least-squares line. b. Interpret the value of \(b\). c. What happens if the line in Part (a) is used to predict the myoglobin level for a finishing time of \(8 \mathrm{hr}\) ? Is this reasonable? Explain.

Short Answer

Expert verified
The least-squares line is the equation obtained in Step 1 and it gives the best fit for the given data. The value of b, obtained in Step 2, predicts the myoglobin level at zero time, however, this prediction may not be meaningful based on the context. The prediction for the myoglobin level at 8 hours falls outside the range of provided data, so the validity of this prediction should be questioned due to extrapolation.

Step by step solution

01

Find the Equation of the Least-Squares Line

To find the equation of the least-squares line, the following formulas should be used which are derived from statistical theory: \(m = \frac{n(\Sigma xy) - (\Sigma x)(\Sigma y)}{n(\Sigma x^2) - (\Sigma x)^2}\) for the slope and \(b = \frac{\Sigma y - m(\Sigma x)}{n}\) for the y-intercept where n is the total number of data points.
02

Interpret the Value of b

Once the equation for the least-squares line has been derived, the y-intercept (b) can be interpreted as the estimated myoglobin level when the finishing time is zero. However, it does not make much sense in this context, since a finishing time of zero hours is not possible in a triathlon.
03

Predict the Myoglobin Level for 8 Hours

Using the derived least-squares line, predict the myoglobin level for a finishing time of 8 hours. This would be done by inputting x = 8 into the equation.
04

Analyze the Result

Evaluate whether this prediction is reasonable or not. This can be assessed by comparing the predicted value with the given dataset. Bear in mind that this is an extrapolation beyond the given data, as 8 hours is outside the range of finishing times provided. Extrapolation can lead to unreliable predictions.
05

Perform Necessary Computational Calculations

Perform the necessary computations for the aforementioned steps.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Myoglobin Levels
Myoglobin is a protein in heart and skeletal muscles that binds oxygen, facilitating the delivery of oxygen to the mitochondria where it is used to produce energy. In sports science, understanding myoglobin levels can be critical as they often increase following muscle damage, and thus can serve as an indicator of muscle stress and endurance exercise impact. During a triathlon—a demanding endurance sport involving swimming, cycling, and running—athletes' muscles are under extreme conditions which can influence myoglobin levels.

From a physiological perspective, myoglobin helps to explain the dynamics of endurance sports and recovery. When scientists investigate myoglobin levels post-triathlon, they're examining how the body copes with prolonged, strenuous exercise. This can provide valuable insights for training regimes and recovery strategies, enabling athletes to maximize their performance while minimizing the risk of injury.
Triathlon Performance Analysis
In the context of triathlons, performance analysis involves examining various data, such as finishing times and physiological biomarkers like myoglobin levels. This analysis helps to draw correlations between an athlete's endurance and the physical responses of their body. Performance can ultimately be influenced by numerous factors, including training intensity, nutrition, rest, and genetics.

By analyzing performance data, coaches and sport scientists can identify strengths and weaknesses in an athlete's endurance capability. It's a multifaceted approach that allows a thorough investigation into how different elements of training and recovery contribute to overall athletic performance. This often involves statistical analysis of the data collected, where patterns, trends, and predictions can provide actionable insights to optimize an athlete’s training and performance.
Scatterplot Interpretation
A scatterplot is a type of graph used to display values for typically two variables for a set of data, and it's particularly useful for spotting trends, correlations, or patterns. In the exercise, the scatterplot represents the relationship between triathlon finishing times and myoglobin levels.

Interpreting a Scatterplot

When analyzing a scatterplot, one looks for the overall direction (positive, negative, or none), shape, and strength of the relationship between variables. Patterns may suggest relationships between the variables, though they do not confirm causation. An outlier—an observation distinctly apart from the other data—can significantly affect the relationship and any statistical calculations, such as the fitting of a least-squares line.
Statistical Theory
Statistical theory provides the foundation for analyzing and interpreting data. In the case of the provided exercise, statistical theory underpins the method to obtain the least-squares line, a concept used to find the line that best fits the data points in a scatterplot. This line minimizes the squared differences (residuals) between the observed values and the values predicted by the line.

Through statistical theory, one can establish a linear relationship between two variables, like finishing times and myoglobin levels, by calculating the slope (m) and y-intercept (b) of the least-squares line. Understanding the meaning of the slope and the y-intercept in context is crucial; for instance, the y-intercept in this context—while mathematically significant—is not practically interpretable due to finishing times not possibly equalling zero. Statistical theory also tells us about the limitations of our analysis, such as the potential for unreliable predictions when extrapolating beyond the observed data range.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A study was carried out to investigate the relationship between the hardness of molded plastic (y, in Brinell units) and the amount of time elapsed since termination of the molding process (x, in hours). Summary quantities include n 5 15, SSResid 5 1235.470, and SSTo 5 25,321.368. Calculate and interpret the coefficient of determination.

The paper "Root Dentine Transparency: Age Determination of Human Teeth Using Computerized Densitometric Analysis" (American Journal of Physical Anthropology [1991]: 25-30) reported on an investigation of methods for age determination based on tooth characteristics. With \(y=\) age (in years) and \(x=\) percentage of root with transparent dentine, a regression analysis for premolars gave \(n=36\), SSResid \(=5987.16\), and SSTo \(=\) 17,409.60. Calculate and interpret the values of \(r^{2}\) and \(s_{e}\)

The paper "A Cross-National Relationship Betwee Sugar Consumption and Major Depression?" (Depression and Anxiety [2002]: \(118-120\) ) concluded that there was a correlation between refined sugar consumption (calories per person per day) and annual rate of major depression (cases per 100 people) based on data from 6 countries. $$ \begin{array}{lcc} \text { Country } & \text { Consumption Rate } \\ \hline \text { Korea } & 150 & 2.3 \\ \text { United States } & 300 & 3.0 \\ \text { France } & 350 & 4.4 \\ \text { Germany } & 375 & 5.0 \\ \text { Canada } & 390 & 5.2 \\ \text { New Zealand } & 480 & 5.7 \\ & & \\ \hline \end{array} $$ a. Compute and interpret the correlation coefficient for this data set. b. Is it reasonable to conclude that increasing sugar consumption leads to higher rates of depression? Explain. c. Do you have any concerns about this study that would make you hesitant to generalize these conclusions to other countries?

Peak heart rate (beats per minute) was determined both during a shuttle run and during a 300 -yard run for a sample of \(n=10\) individuals with Down syndrome ("Heart Rate Responses to Two Field Exercise Tests by Adolescents and Young Adults with Down Syndrome," Adapted Physical Activity Quarterly [1995]: 43-51), resulting in the following data: $$ \begin{array}{llllllll} \text { Shuttle } & 168 & 168 & 188 & 172 & 184 & 176 & 192 \\ \text { 300-yd } & 184 & 192 & 200 & 192 & 188 & 180 & 182 \\ \text { Shuttle } & 172 & 188 & 180 & & & & \\ \text { 300-yd } & 188 & 196 & 196 & & & & \end{array} $$ a. Construct a scatterplot of the data. What does the scatterplot suggest about the nature of the relationship between the two variables? b. With \(x=\) shuttle run peak rate and \(y=300\) -yd run peak rate, calculate \(r\). Is the value of \(r\) consistent with your answer in Part (a)? c. With \(x=300\) -yd peak rate and \(y=\) shuttle run peak rate, how does the value of \(r\) compare to what you calculated in Part (b)?

The paper "Accelerated Telomere Shortening in Response to Life Stress" (Proceedings of the National Academy of Sciences [2004]: 17312-17315) described a study that examined whether stress accelerates aging at a cellular level. The accompanying data on a measure of perceived stress \((x)\) and telomere length \((y)\) were read from a scatterplot that appeared in the paper. Telomere length is a measure of cell longevity. $$ \begin{array}{rrrl} \begin{array}{l} \text { Perceived } \\ \text { Stress } \end{array} & \begin{array}{l} \text { Telomere } \\ \text { Length } \end{array} & \begin{array}{l} \text { Perceived } \\ \text { Stress } \end{array} & \begin{array}{l} \text { Telomere } \\ \text { Length } \end{array} \\ \hline 5 & 1.25 & 20 & 1.22 \\ 6 & 1.32 & 20 & 1.3 \\ 6 & 1.5 & 20 & 1.32 \\ 7 & 1.35 & 21 & 1.24 \\ 10 & 1.3 & 21 & 1.26 \\ 11 & 1 & 21 & 1.3 \\ 12 & 1.18 & 22 & 1.18 \\ 13 & 1.1 & 22 & 1.22 \\ 14 & 1.08 & 22 & 1.24 \\ 14 & 1.3 & 23 & 1.18 \\ 15 & 0.92 & 24 & 1.12 \\ 15 & 1.22 & 24 & 1.5 \\ 15 & 1.24 & 25 & 0.94 \\ 17 & 1.12 & 26 & 0.84 \\ 17 & 1.32 & 27 & 1.02 \\ 17 & 1.4 & 27 & 1.12 \\ 18 & 1.12 & 28 & 1.22 \\ 18 & 1.46 & 29 & 1.3 \\ 19 & 0.84 & 33 & 0.94 \\ \hline \end{array} $$ a. Compute the equation of the least-squares line. b. What is the value of \(r^{2}\) ? c. Does the linear relationship between perceived stress and telomere length account for a large or small proportion of the variability in telomere length? Justify your answer.

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.