Our sample and data was collected via face to face or telephone
interviews, fax and e-mail questionnaires; the respondent was
instructed to focus on the staff, section chief, and manager of the
logistics enterprise, which is a member of the KTA (Korea trucking
association). The KTA represents the only leading group of logistics
companies in Korea. This questionnaire was initially disseminated
in February 2011, and completed in April 2011. A total of 156
copies of the questionnaires were collected and 129 copies of the
questionnaires provided all of the information required (these
questionnaires came from different areas of South Korea). The 129
logistics enterprises represent the various kinds of operational
areas: 23.3% are in the integrated logistics sector, 60.5% in the
transportation sector, 5.4% in the storage sector, 6.0% and 4.7% in
the loading and unloading sector, 1.6% in the logistics forwarding
sector, 3.1% in the delivery sector, and the rest in other logistics
sectors. It is important to deal with the potential problem of a nonresponse
bias. To deal with this issue, we tested for a nonresponse
bias using a comparison of early and late respondents as
recommended by Armstrong and Overton (1977). The 129
questionnaires were divided into two groups based on their
completion date. A t-test is used to determine whether there were
any differences in the answers between the early and late groups