444K.H.Lai etal. /TransportationResearch PartE38 (2002)439-456measurement instrument. The instrument is pre-tested, modified, and used to capture data in across-sectional survey of transport logistics service providers.The following paragraphs describethese processes in detail.4.1.Domainspecificationand instrumentdevelopmentIntheprevious discussion,SCPintransportlogistics isidentifiedasa three-factormodel.Inline with SCOR, SES and SEC are customer-facing measures and concerned withthereliability(REL)andresponsiveness(RES)of a supplychainprocessperformedfor shippersandcon-signees,respectively.These two service-oriented components are operationalized bymodifying thereliability and responsivenessdimensions of the SERVQUAL instrumentdevelopedbyPara-suraman et al. (1988). I The modified measures gauge the service effectiveness performed re-spectively for shippers (SES-REL and SES-RES) and consignees (SEC-REL and SEC-RES).OE is concerned with the eficient use of resources in performing transport logistics services.InSCOR, there are two aspects of OE: cost-related and asset-related. In line with Mentzer andKonrad (1991),the cost-related aspect of OE (OE-COST)is operationalized by five broad cate-gories of logistics performance:transportation, warehousing, costs associated with thefacilitiesand manpowerused in providing the services, orderprocessing, and logistics administration.Theasset-related aspectofOE(OE-ASSET)is developed on thebasis of thethreemeasures suggestedin SCOR: cash-to-cash cycle time, utilization of facilities and manpower in providing the services,and assetturns.A total of 26 measurement items are generated for the measurement instrument: nine for SES,eight for OE and nine for SEC as shown in Appendix A. An example is added to each item toenrich the content and improve the comprehensiveness of the item in the instrument.2 Contentvalidity is concerned with the extent to which a specific set of items reflects a content domain(DeVellis, 1991).Assessing content validity helps to ensure that the items used to operationalizethe construct actually measure what they are supposed to measure (Churchill, 1979).We per-formed a content validation test by inviting some experts to review the measuring items to ensurethat they are representative of our SCP conceptualization in transport logistics.3Several changesin the wording were made and the items were subject to further refinement in a pilot test.'SERVQUAL is a widely accepted instrument to measure service quality across a wide variety of service domains,see Parasuraman et al. (1988,1994)for details.There are five dimensions in SERVQUAL:reliability,responsivenessassurances,empathy,and tangibility.The service-oriented component of the SCP construct regarding reliability andresponsiveness in this studyare developed on the basis of thefirsttwodimensions in SERVQUALbecauseof theirwideacceptanceand robustness in the literature.2The measurement items are measured on a five-point scale, ranging from an anchor Imuch worse than thecompetition,2-worse than thecompetition,3-same as the competition,4better than the competition, andsuperiorto the competition.Respondents wereinvited to evaluatetheperformance of theircompanies withrespectto the items on the five-point scale.The measurement items were included in a structured questionnaire for contentvalidation and refinement.Two neutral academics in the transport logisticsfield and two industry practitioners were invited toreviewtheitemsto ensure the relevance and clarity of the wording for the items in the instrument. Each of the reviewers was briefed onthe purpose of the study and asked to criticallyreview the items for completeness, understandability,terminology,andambiguity
measurement instrument. The instrument is pre-tested, modified, and used to capture data in a cross-sectional survey of transport logistics service providers. The following paragraphs describe these processes in detail. 4.1. Domain specification and instrument development In the previous discussion, SCP in transport logistics is identified as a three-factor model. In line with SCOR, SES and SEC are customer-facing measures and concerned with the reliability (REL) and responsiveness (RES) of a supply chain process performed for shippers and consignees, respectively. These two service-oriented components are operationalized by modifying the reliability and responsiveness dimensions of the SERVQUAL instrument developed by Parasuraman et al. (1988). 1 The modified measures gauge the service effectiveness performed respectively for shippers (SES-REL and SES-RES) and consignees (SEC-REL and SEC-RES). OE is concerned with the efficient use of resources in performing transport logistics services. In SCOR, there are two aspects of OE: cost-related and asset-related. In line with Mentzer and Konrad (1991), the cost-related aspect of OE (OE-COST) is operationalized by five broad categories of logistics performance: transportation, warehousing, costs associated with the facilities and manpower used in providing the services, order processing, and logistics administration. The asset-related aspect of OE (OE-ASSET) is developed on the basis of the three measures suggested in SCOR: cash-to-cash cycle time, utilization of facilities and manpower in providing the services, and asset turns. A total of 26 measurement items are generated for the measurement instrument: nine for SES, eight for OE and nine for SEC as shown in Appendix A. An example is added to each item to enrich the content and improve the comprehensiveness of the item in the instrument. 2 Content validity is concerned with the extent to which a specific set of items reflects a content domain (DeVellis, 1991). Assessing content validity helps to ensure that the items used to operationalize the construct actually measure what they are supposed to measure (Churchill, 1979). We performed a content validation test by inviting some experts to review the measuring items to ensure that they are representative of our SCP conceptualization in transport logistics. 3 Several changes in the wording were made and the items were subject to further refinement in a pilot test. 1 SERVQUAL is a widely accepted instrument to measure service quality across a wide variety of service domains, see Parasuraman et al. (1988, 1994) for details. There are five dimensions in SERVQUAL: reliability, responsiveness, assurances, empathy, and tangibility. The service-oriented component of the SCP construct regarding reliability and responsiveness in this study are developed on the basis of the first two dimensions in SERVQUAL because of their wide acceptance and robustness in the literature. 2 The measurement items are measured on a five-point scale, ranging from an anchor 1––much worse than the competition, 2––worse than the competition, 3––same as the competition, 4––better than the competition, and 5––superior to the competition. Respondents were invited to evaluate the performance of their companies with respect to the items on the five-point scale. The measurement items were included in a structured questionnaire for content validation and refinement. 3 Two neutral academics in the transport logistics field and two industry practitioners were invited to review the items to ensure the relevance and clarity of the wording for the items in the instrument. Each of the reviewers was briefed on the purpose of the study and asked to critically review the items for completeness, understandability, terminology, and ambiguity. 444 K.H. Lai et al. / Transportation Research Part E38 (2002) 439–456
445K.H.Laietal./TransportationResearchPartE38(2002)439-456Table 2Summary measurement resultsS.D.Number of itemsMeanAlphaFactorsRange of item-to-total correlations545SES-REL4.12 (3.80)0.52 (0.49)0.74 (0.73)0.450.57 (0.360.64)SES-RES4.04 (3.92)0.48 (0.53)0.76 (0.77)0.460.63 (0.450.68)OE-COST3.65 (3.69)0.73 (0.49)0.87 (0.70)0.620.77 (0.420.55)354OE-ASSET3.74 (3.65)0.41 (0.62)0.80 (0.79)0.560.72 (0.580.74)SEC-REL4.03 (3.87)0.63 (0.42)0.86 (0.66)0.57-0.75 (0.380.52)SEC-RES4.01 (3.84)0.52 (0.46)0.83 (0.60)0.61-0.70 (0.300.61)Note: Entries in theparentheses arepilottest results.4.2. Pilot testA pilot test was carried out to further test and refine the instrument. The pilot test was con-ducted with 30 postgraduate students studying a part-time Master's degree in InternationalShipping and Transport Logistics at The Hong Kong Polytechnic University (who were full-timetransport logistics practitioners) and a convenient sample of 20 practitioners in the field. 4 A totalof 32valid responses were collected inthepilot test.Based on the32responses,preliminaryvalidity of the instrument was established on the basis of two criteria: content validity, andconstruct validity from an item-to-total correlation analysis and reliability test. 6 The results ofthe pilot test are given in Table 2.4.3.Data collectionTo further explorethe SCP construct, thefinal version ofthequestionnaire was mailed, with acoveringletterand a self-addressedprepaid return envelope, to thecomplete sampleof all 924companies in the Schednet Asian Logistics Directory (Schednet, 2001), in which all the companiesinvolved in transport logistics in Hong Kong are listed.7Weused thekey informant strategy tocarry out the survey research (Phillips and Bagozzi, 1986). Target respondents were generalmanagers or logistics managers of the sampled companies.The questionnaire was mailed twice:one month after the first mailing, the questionnaire was again mailed to the non-respondents.4The pilot test samples were asked to complete the questionnaire and to offer suggestionsfor improvement of themeasurement instrument.The pilot test resulted in minormodifications to the wording and examples provided in somemeasurementitems5Content validity is ensured because themeasurement items were derived andmodifiedfrom established measures,aswell as from suggestions from academics and practitioners in the field.Moreover, the pilot test respondents indicatedthat the content of SCP in transport logistics is well represented by the items included in the measurement instrument.These procedures are entirely consistent with those required for attaining high content validity.The construct validity of the SCP scalewas examined using a reliabilitytest with the coefficient alpha computed foreach of the sub-dimensions, e.g.SES-REL, and item-to-total correlation analysis.These procedures resulted in a set ofitems with coefficient alpha values all higher than 0.60 and all item loadings in item-to-total correlation analysis weregreater than 0.307The sample represents four broad categories of companies in the industry: sea transport,freightforwarding,airtransport, third-party logistics services.8 These executives were targeted because they possess expert knowledge of SCP in transport logistics in theircompanies
4.2. Pilot test A pilot test was carried out to further test and refine the instrument. The pilot test was conducted with 30 postgraduate students studying a part-time Master’s degree in International Shipping and Transport Logistics at The Hong Kong Polytechnic University (who were full-time transport logistics practitioners) and a convenient sample of 20 practitioners in the field. 4 A total of 32 valid responses were collected in the pilot test. Based on the 32 responses, preliminary validity of the instrument was established on the basis of two criteria: content validity, 5 and construct validity from an item-to-total correlation analysis and reliability test. 6 The results of the pilot test are given in Table 2. 4.3. Data collection To further explore the SCP construct, the final version of the questionnaire was mailed, with a covering letter and a self-addressed prepaid return envelope, to the complete sample of all 924 companies in the Schednet Asian Logistics Directory (Schednet, 2001), in which all the companies involved in transport logistics in Hong Kong are listed. 7 We used the key informant strategy to carry out the survey research (Phillips and Bagozzi, 1986). Target respondents were general managers or logistics managers of the sampled companies. 8 The questionnaire was mailed twice: one month after the first mailing, the questionnaire was again mailed to the non-respondents. 4 The pilot test samples were asked to complete the questionnaire and to offer suggestions for improvement of the measurement instrument. The pilot test resulted in minor modifications to the wording and examples provided in some measurement items. 5 Content validity is ensured because the measurement items were derived and modified from established measures, as well as from suggestions from academics and practitioners in the field. Moreover, the pilot test respondents indicated that the content of SCP in transport logistics is well represented by the items included in the measurement instrument. These procedures are entirely consistent with those required for attaining high content validity. 6 The construct validity of the SCP scale was examined using a reliability test with the coefficient alpha computed for each of the sub-dimensions, e.g. SES-REL, and item-to-total correlation analysis. These procedures resulted in a set of items with coefficient alpha values all higher than 0.60 and all item loadings in item-to-total correlation analysis were greater than 0.30. Table 2 Summary measurement results Factors Number of items Mean S.D. Alpha Range of item-to-total correlations SES-REL 5 4.12 (3.80) 0.52 (0.49) 0.74 (0.73) 0.45–0.57 (0.36–0.64) SES-RES 4 4.04 (3.92) 0.48 (0.53) 0.76 (0.77) 0.46–0.63 (0.45–0.68) OE-COST 5 3.65 (3.69) 0.73 (0.49) 0.87 (0.70) 0.62–0.77 (0.42–0.55) OE-ASSET 3 3.74 (3.65) 0.41 (0.62) 0.80 (0.79) 0.56–0.72 (0.58–0.74) SEC-REL 5 4.03 (3.87) 0.63 (0.42) 0.86 (0.66) 0.57–0.75 (0.38–0.52) SEC-RES 4 4.01 (3.84) 0.52 (0.46) 0.83 (0.60) 0.61–0.70 (0.30–0.61) Note: Entries in the parentheses are pilot test results. 7 The sample represents four broad categories of companies in the industry: sea transport, freight forwarding, air transport, third-party logistics services. 8 These executives were targeted because they possess expert knowledge of SCP in transport logistics in their companies. K.H. Lai et al. / Transportation Research Part E38 (2002) 439–456 445