Is the slope of the least-squares line positive or negative

Reference no: EM131008558

The article "Air Pollution and Medical Care Use by Older Americans" (Health Affairs [2002]: 207-214) gave data on a measure of pollution (in micro- grams of particulate matter per cubic meter of air) and the cost of medical care per person over age 65 for six geographical regions of the United States:

Region	Pollution	Cost of Medical Care
6.17		-0.08
8.06		0.25
8.62		-0.14
10.56		0
12.45		0.08
11.99		0.03
12.5		-0.07
17.98		0.29
18.29		0.23
19.89		0.24
20.25		0.19
19.07		0.14
17.73		0.05
19.62		0.07

Mean Temperature (x) Net Directionality (y)

North	30.0	915
Upper South	31.8	891
Deep South	32.1	968
West South	26.8	972
Big Sky	30.4	952
West	40.0	899

a. Construct a scatterplot of the data. Describe any interesting features of the scatterplot.

b. Find the equation of the least-squares line describing the relationship between y 5 medical cost and x 5 pollution.

c. Is the slope of the least-squares line positive or negative? Is this consistent with your description of the relationship in Part (a)?

d. Do the scatterplot and the equation of the least- squares line support the researchers' conclusion that elderly people who live in more polluted areas have higher medical costs? Explain.

Reference no: EM131008558

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