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Beer and BAC How well does the number of beers a person drinks predict his or her blood alcohol content (BAC)? Sixteen volunteers aged 21or older with an initial BAC of 0took part in a study to find out. Each volunteer drank a randomly assigned number of cans of beer. Thirty minutes later, a police officer measured their BAC. A least-squares regression analysis was performed on the data using x=number of beers and y=BAC. Here is a residual plot and a histogram of the residuals. Check whether the conditions for performing inference about the regression model are met.

Short Answer

Expert verified

Normal, equal variance, random, independent, and linear are the five requirements for regression inferences.

Step by step solution

01

Step  1 : Given Information

We have to explain that whether the state for performing inference about the regression model are met or not.

02

Simplification

Normal,equalvariance,random,independent,andlineararethefiverequirementsforregressioninferences.
The reason for this is that the histogram is bell-shaped.
The reason for this is that the vertical spread of points in the residual figure is roughly the same everywhere, therefore equal variance is satisfied.
The explanation for this is that the subjects were assigned at random. Because the respondents were randomized at random, independent: satisfied. Because all points in the residual figure are centred around zero, the linear condition is satisfied.
As a result, all states or requirements have been met.

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Most popular questions from this chapter

T12.3 Inference about the slope ฮฒ1 of a least-squares regression line is based on which of
the following distributions?
a. The tdistribution with nโˆ’1 degrees of freedom
b. The standard Normal distribution
c. The chi-square distribution with nโˆ’1 degrees of freedom
d. The t distribution with n-2 degrees of freedom
e. The Normal distribution with mean ฮผ and standard deviation ฯƒ.

A survey firm wants to ask a random sample of adults in Ohio if they support an increase in the state sales tax from 5.75%to 6%, with the additional revenue going to education. Let p^denote the proportion in the sample who say that they support the increase. Suppose that 40%of all adults in Ohio support the increase. If the survey firm wants the standard deviation of the sampling distribution of p^to equal 0.01,how large a sample size is needed?

a.1500

b. 2400

c.2401

d.2500

e.9220

If P(A)=0.2and P(B)=0.52 and events A and B are independent, what is P(A or B)?

a. 0.1248

b. 0.28

c. 0.6352

d. 0.76

e. The answer cannot be determined from the given information.

T12.12 Foresters are interested in predicting the amount of usable lumber they can harvest from various tree species. They collect data on the diameter at breast height (DBH) in inches and the yield in board feet of a random sample of 20 Ponderosa pine trees that have been harvested. (Note that a board foot is defined as a piece of lumber 12 inches by 12 inches by 1 inch.) Here is a scatterplot of the data.

a. Here is some computer output and a residual plot from a least-squares regression on these data. Explain why a linear model may not be appropriate in this case.

The foresters are considering two possible transformations of the original data: (1) cubing the diameter values or (2) taking the natural logarithm of the yield measurements. After transforming the data, a least-squares regression analysis is performed. Here is some computer output and a residual plot for each of the two possible regression models:

b. Use both models to predict the amount of usable lumber from a Ponderosa pine with diameter 30 inches.
c. Which of the predictions in part (b) seems more reliable? Give appropriate evidence to support your choice.

Predicting height Using the health records of every student at a high school, the school nurse created a scatterplot relating y=height (in centimeters) to x=age (in years). After verifying that the conditions for the regression model were met, the nurse calculated the equation of the population regression line to be ฮผy=105+4.2xwith ฯƒ=7cm.

a. According to the population regression line, what is the average height of 15-year-old students at this high school?

b. About what percent of 15-year-old students at this school are taller than 180cm?

c. If the nurse used a random sample of 50students from the school to calculate the regression line instead of using all the students, would the slope of the sample regression line be exactly 4.2? Explain your answer.

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