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臺大管理論叢
第
27
卷第
3
期
147
pre-entry background information is not included in the estimation model because the fixed-
effects model automatically controls the time-invariant firm effects. Table 1 presents a
summary of the variables and their measurements.
Table 1 Variables and Measurements
Variables
Measurements
Intra-industry performance of firm
i
at
t
(Increases in sales)
= Addition in total number of subscribers for firm
i
from
t
-1 to
t
,
excluding the subscribers obtained through acquisitions
Firm size at
t
-1
= Total number of subscribers for firm
i
at
t
-1
Growth of industry subscribers (
t
) = Ln (industry subscribers at
t
divided by industry subscribers at
t
-1)
CR4
= Sum of market share of the top four firms in the industry of
cellular phone services
N of acquisitions (
t
)
= Number of acquisitions firm
i
completed at
t
Size of TMT
= Number of executives at firm
i
ʼs TMT at
t
# Execs w/ missing info
= Number of executives with missing information
Below industry median firm size = 1 if firm subscribers at
t
-1 is below industry median
Focal year is before digital
technology regime
= 1 if focal year is before 1991, and 0 otherwise
Industry age
= Total number of years the industry has existed
= focal year-1983 + 1
Intra-industry experience addition
of TMT at
t
= Addition in the average year of cellular phone service industry
experience of firm
i
ʼs TMT members at year
t
Intra-industry ties to industry
associations-CTIA of TMT at
t
-1
= Total number of TMT members who had been a board member
of CTIA prior to the focal year for firm
i
at year
t
-1
Intra-industry ties to other cell-
phone operators of TMT at
t
-1
= Total number of other cellular phone service operators that all
TMT members had been a top manager prior to entering firm
i
at
year
t
-1
Extra-industry ties to other firms
of TMT at
t
-1
= Total number of firms in other industries that TMT members had
been a top manager prior to entering firm
i
at year
t
-1
5.3 Data Sources
Data on the sampling firms and their TMT compositions are obtained primarily from the
following sources: Phillips Publishing Telephone Industry Directory, Mobile
Communications Directory, Cellular/Mobile Communications Directory, Wireless Industry
Directory, Telephone Industry Directory and Sourcebook, Telecom Factbook 1985-1988,
Corporate Affiliations, firms’ U.S. Securities and Exchange Commission (SEC) filings, and
Moody’s Unlisted OTC Manual, OTC Manual, and Industry Manual. To determine TMT