Chapter 11: Q2E (page 649)
Give the slope and y-intercept for each of the lines graphed in Exercise 11.1.
Short Answer
- Slope = 1, y-intercept = 0
- Slope = -1, y-intercept = 3
- Slope = 1/5, y-intercept = 6/5
- Slope = 9/8, y-intercept = 15/4
Chapter 11: Q2E (page 649)
Give the slope and y-intercept for each of the lines graphed in Exercise 11.1.
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Get started for freeVoltage sags and swells. The power quality of a transformer is measured by the quality of the voltage. Two causes of poor power quality are "sags" and "swells." A sag is an unusual dip and a swell is an unusual increase in the voltage level of a transformer. The power quality of transformers built in Turkey was investigated in Electrical Engineering (Vol. 95, 2013). For a sample of 103 transformers built for heavy industry, the mean number of sags per week was 353 and the mean number of swells per week was 184. Assume the standard deviation of the sag distribution is 30 sags per week and the standard deviation of the swell distribution is 25 swells per week.
a. For a sag distribution with any shape, what proportion of transformers will have between 263 and 443 sags per week? Which rule did you apply and why?
b. For a sag distribution that is mound-shaped and symmetric, what proportion of transformers will have between 263 and 443 sags per week? Which rule did you apply and why?
c. For a swell distribution with any shape, what proportion of transformers will have between 109 and 259 swells per week? Which rule did you apply and why?
d. For a swell distribution that is mound-shaped and symmetric, what proportion of transformers will have between 109 and 259 swells per week? Which rule did you apply and why?
The equation for a straight line (deterministic model) is
If the line passes through the point (-2, 4), then x = -2, y = 4 must satisfy the equation; that is,
Similarly, if the line passes through the point (4, 6), then x = 4, y = 6 must satisfy the equation; that is,
Use these two equations to solve for and ; then find the equation of the line that passes through the points (-2, 4) and (4, 6).
Visually compare the scatter plots shown below. If a least squares line were determined for each data set, which do you think would have the smallest variance ? Explain.
Why do we generally prefer a probabilistic model to a deterministic model? Give examples for when the two types of models might be appropriate.
Do nice guys really finish last in business? Refer to the Nature (March 20, 2008) study of whether “nice guys finish last” in business, Exercise 11.18 (p. 653). Recall that college students repeatedly played a version of the game “prisoner’s dilemma,” where competitors choose cooperation, defection, or costly punishment. At the conclusion of the games, the researchers recorded the average payoff and the number of times punishment was used for each player. Based on a scatter plot of the data, the simple linear regression relating average payoff (y) to punishment use (x) resulted in SSE = 1.04.
a. Assuming a sample size of n = 28, compute the estimated standard deviation of the error distribution, s.
b. Give a practical interpretation of s.
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