Chapter 2: Problem 204
Use technology to find the regression line to predict \(Y\) from \(X\). $$\begin{array}{llllll} \hline X & 3 & 5 & 2 & 7 & 6 \\\Y & 1 & 2 & 1.5 & 3 & 2.5 \\ \hline\end{array}$$
Chapter 2: Problem 204
Use technology to find the regression line to predict \(Y\) from \(X\). $$\begin{array}{llllll} \hline X & 3 & 5 & 2 & 7 & 6 \\\Y & 1 & 2 & 1.5 & 3 & 2.5 \\ \hline\end{array}$$
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Get started for freeCreate Your Own: Bubble Plot Using any of the datasets that come with this text that include at least three quantitative variables (or any other dataset that you find interesting and that meets this condition), use statistical software to create a bubble plot of the data. Indicate the dataset, the cases, and the variables that you use. Specify which variable represents the size of the bubble. Comment (in context) about any interesting features revealed in your plot.
Indicate whether the five number summary corresponds most likely to a distribution that is skewed to the left, skewed to the right, or symmetric. (0,15,22,24,27)
Ages of Husbands and Wives Suppose we record the husband's age and the wife's age for many randomly selected couples. (a) What would it mean about ages of couples if these two variables had a negative relationship? (b) What would it mean about ages of couples if these two variables had a positive relationship? (c) Which do you think is more likely, a negative or a positive relationship? (d) Do you expect a strong or a weak relationship in the data? Why? (e) Would a strong correlation imply there is an association between husband age and wife age?
Two variables are defined, a regression equation is given, and one data point is given. (a) Find the predicted value for the data point and compute the residual. (b) Interpret the slope in context. (c) Interpret the intercept in context, and if the intercept makes no sense in this context, explain why. Study \(=\) number of hours spent studying for an exam, Grade \(=\) grade on the exam. \(\widehat{\text { Grade }}=41.0+3.8\) (Study); data point is a student who studied 10 hours and received an 81 on the exam.
Donating Blood to Grandma? Can young blood help old brains? Several studies \(^{32}\) in mice indicate that it might. In the studies, old mice (equivalent to about a 70 -year-old person) were randomly assigned to receive blood plasma either from a young mouse (equivalent to about a 25 -year-old person) or another old mouse. The mice receiving the young blood showed multiple signs of a reversal of brain aging. One of the studies \(^{33}\) measured exercise endurance using maximum treadmill runtime in a 90 -minute window. The number of minutes of runtime are given in Table 2.17 for the 17 mice receiving plasma from young mice and the 13 mice receiving plasma from old mice. The data are also available in YoungBlood. $$ \begin{aligned} &\text { Table 2.17 Number of minutes on a treadmill }\\\ &\begin{array}{|l|lllllll|} \hline \text { Young } & 27 & 28 & 31 & 35 & 39 & 40 & 45 \\ & 46 & 55 & 56 & 59 & 68 & 76 & 90 \\ & 90 & 90 & 90 & & & & \\ \hline \text { Old } & 19 & 21 & 22 & 25 & 28 & 29 & 29 \\ & 31 & 36 & 42 & 50 & 51 & 68 & \\ \hline \end{array} \end{aligned} $$ (a) Calculate \(\bar{x}_{Y},\) the mean number of minutes on the treadmill for those mice receiving young blood. (b) Calculate \(\bar{x}_{O},\) the mean number of minutes on the treadmill for those mice receiving old blood. (c) To measure the effect size of the young blood, we are interested in the difference in means \(\bar{x}_{Y}-\bar{x}_{O} .\) What is this difference? Interpret the result in terms of minutes on a treadmill. (d) Does this data come from an experiment or an observational study? (e) If the difference is found to be significant, can we conclude that young blood increases exercise endurance in old mice? (Researchers are just beginning to start similar studies on humans.)
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