1. In a PC World comparison of computer hard drives, data describing the drives included the following variables: price (dollars), disk capacity (gigabytes), and rotational speed (RPM). The data are in file XR17027. With y 5 price, x1 5 disk capacity, and x2 5 rotational speed (coded as 1 5 7200 RPM and 0 5 5400 RPM), determine the linear regression equation for estimating price as a function of the two predictor variables and interpret the partial regression coefficients. For a given storage capacity, how much extra would one expect to pay for a hard drive with the higher rotational speed? Source: Stan Miastkowski,
2. For a small sample of suburban homes recently sold, the selling price ($), living space (square feet), and suburban area (Sunny Haven, Easy Acres, or Rolling Hills) have been recorded. Given the data shown here, determine the linear regression equation for estimating selling price based on the other variables. For any qualita- tive variables that are used, be sure to specify the coding strategy employed for each. Comment on the explanatory power of the regression equation and interpret the partial regression coefficients.
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"Livin' Large," PC World, March 2001, p. 109.
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Home
|
Price
|
Space
|
Area
|
|
17.28 A researcher has observed 50 automatic teller
|
1
|
167,900
|
2860
|
Easy
|
|
machine (ATM) users outside the gift shop of a museum,
|
2
|
184,800
|
2050
|
Sunny
|
|
and the data are in file XR17028. With y 5 amount with-
|
3
|
161,000
|
2110
|
Rolling
|
|
drawn (dollars), x1 5 time required for the transaction
|
4
|
160,800
|
2950
|
Easy
|
|
(seconds), and x2 5 gender (1 5 female, 0 5 male),
|
5
|
148,200
|
1570
|
Sunny
|
|
determine the linear regression equation for estimating
|
6
|
128,600
|
1860
|
Rolling
|
|
the withdrawal amount as a function of the two predic-
|
7
|
145,700
|
2620
|
Rolling
|
|
tor variables and interpret the partial regression coef-
|
8
|
178,500
|
2010
|
Sunny
|
|
ficients. According to the equation, how much difference
|
9
|
146,100
|
2710
|
Easy
|
|
does gender tend to make in the amount withdrawn?
|
10
|
146,300
|
2200
|
Rolling
|