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. A group of researchers were interested in determining the likelihood that a business currently purchasing office supplies via a catalog would switch to purchasing from theWeb site of the same supplier. To do this, they performed an online survey using the business clients of a large Australian-based stationery provider with both a catalog and a Web-based business.21 Results from 1809 firms, all currently purchasing via the catalog, were obtained. The following table summarizes the regression model.
$1rn    Variable$1rn $1rn $1rn $1rn $1rn $1rn $1rn $1rn $1rn $1rn $1rn  b$1rn $1rn $1rn $1rn $1rn $1rn t
Staff interpersonal contact with catalog −$1rn $1rn 0.08$1rn $1rn $1rn $1rn    3.34
Trust of supplier$1rn $1rn $1rn $1rn $1rn $1rn $1rn $1rn $1rn $1rn   0.11$1rn $1rn $1rn $1rn  4.66
Web benefits (access and accuracy$1rn $1rn $1rn $1rn  0.08$1rn $1rn $1rn $1rn$1rn 3.92
Previous Web purchases 0$1rn $1rn $1rn $1rn $1rn $1rn    .18 8$1rn $1rn $1rn $1rn $1rn .20
Previous Web information search$1rn $1rn $1rn $1rn    0.08$1rn $1rn $1rn $1rn $1rn 3.47
Key catalog benefits (staff, speed, security) −  0.08$1rn $1rn $1rn $1rn $1rn  3.96
Web benefits (speed and ease of use)$1rn $1rn $1rn   0.36$1rn $1rn $1rn $1rn $1rn    3.97
Problems with Web ordering and delivery −$1rn 0.06$1rn $1rn $1rn $1rn $1rn$1rn 2.65
(a) The F statistic is reported to be 78.15. What degrees of freedom are associated with this statistic?
(b) This F statistic can be expressed in terms of R2 as
F =
_
n − p − 1
p
__
R2
1 − R2
_
Use this relationship to determine R2.
(c) The coefficients listed above are standardized coefficients. These are obtained when each variable is standardized (subtract
its mean, divide by its standard deviation) prior to fitting the regression model. These coefficients then represent the change in
standard deviations of y for a one standard deviation change in x. This typically allows one to determine which independent variables have a greater effect on the dependent variable. Using thisidea, what are the top four variables in this analysis?
Exercises 11.91 to 11.94 use the PRICEPROMO data set shown in Table 11.6 on the next page.
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