# Question

A subset of data read from a graph that appeared in the paper “Decreased Brain Volume in Adults with Childhood Lead Exposure” (Public Library of Science Medicine [May 27, 2008]: e112) was used to produce the following Minitab output, where x = mean childhood blood lead level (mg/dL) and y = brain volume change (percentage). (See Exercise 13.19 for a more complete description of the study described in this paper)

a. What is the equation of the estimated regression line?

b. For this dataset, n 5 100, x 5 11.5, se 5 0.032, and Sxx 5 1764. Estimate the mean brain volume change for people with a childhood blood lead level of 20 mg/dL, using a 90% confidence interval.

c. Construct a 90% prediction interval for brain volume change for a person with a childhood blood lead level of 20 mg/dL.

d. Explain the difference in interpretation of the intervals computed in Parts (b) and (c).

a. What is the equation of the estimated regression line?

b. For this dataset, n 5 100, x 5 11.5, se 5 0.032, and Sxx 5 1764. Estimate the mean brain volume change for people with a childhood blood lead level of 20 mg/dL, using a 90% confidence interval.

c. Construct a 90% prediction interval for brain volume change for a person with a childhood blood lead level of 20 mg/dL.

d. Explain the difference in interpretation of the intervals computed in Parts (b) and (c).

## Answer to relevant Questions

A sample of small cars was selected, and the values of x = horsepower and y = fuel efficiency (mpg) were determined for each car. Fitting the simple linear regression model gave the estimated regression equation y^ = 44.0 2 ...For the cereal data of the previous exercise, the mean x value is 19.21. Would a 95% confidence interval with x* = 20 or x* = 17 be wider? Explain. Answer the same question for a prediction interval. Television is regarded by many as a prime culprit for the difficulty many students have in performing well in school. The article “The Impact of Athletics, Part- Time Employment, and Other Activities on Academic ...A sample of n = 61 penguin burrows was selected, and values of both y = trail length (m) and x 5 soil hardness (force required to penetrate the substrate to a depth of 12 cm with a certain gauge, in kg) were determined for ...The figure at the top of the page is based on data from the article “Root and Shoot Competition Intensity Along a Soil Depth Gradient” (Ecology [1995]: 673– 682). It shows the relationship between aboveground biomass ...Post your question

0