Fig. 1
Profile of participants in the pre-pilot research
| ID | Position | Experience in international business (years) | Number of foreign countries participated in | Number of ICPs involved in |
|---|---|---|---|---|
| Interviewee 1 | Project manager | 24 | 5 | 12 |
| Interviewee 2 | CEO | 40 | 5 | 26 |
| Interviewee 3 | Technical director | 32 | 3 | 20 |
| Interviewee 4 | CEO | 6 | 6 | 8 |
| Interviewee 5 | Retired PM | 30 | 36 | 12 |
| Interviewee 6 | Project manager | 5 | 8 | 8 |
| Interviewee 7 | Project manager | 7 | 1 | 4 |
| Interviewee 8 | CEO | 6 | 2 | 2 |
| Interviewee 9 | CEO | 16 | 5 | 10 |
| Interviewee 10 | CEO | 14 | 3 | 6 |
Final list of CSFs for the success of ICPs
| Group | Variable | CSFs |
|---|---|---|
| Project-related factors | CSF-P-1 | Project size and value |
| CSF-P-2 | Constructability/Complexity | |
| CSF-P-3 | Site management | |
| CSF-P-4 | Accurate initial cost estimates | |
| CSF-P-5 | The formal dispute resolution process | |
| CSF-P-6 | Adequate funding throughout the project | |
| CSF-P-7 | Effective project planning and control | |
| CSF-P-8 | IT support for project management | |
| CSF-P-9 | Appropriate project identification | |
| CSF-P-10 | Effective project management | |
| Human-related factors | CSF-H-1 | Project manager's competency |
| CSF-H-2 | Project manager's experience | |
| CSF-H-3 | Decision-making ability of project manager | |
| CSF-H-4 | Leadership skills of project manager | |
| CSF-H-5 | Project manager's adaptability to make changes in the project plan | |
| CSF-H-6 | Commitment | |
| CSF-H-7 | Troubleshooting skills of project team members (problem-solving) | |
| CSF-H-8 | Multidisciplinary team | |
| Organizational factors | CSF-O-1 | Top management support |
| CSF-O-2 | Company's flexibility | |
| CSF-O-3 | Comprehensive contract documentation | |
| CSF-O-4 | Quality control | |
| CSF-O-5 | Effective project monitoring and control | |
| CSF-O-6 | Clear goals and objectives | |
| CSF-O-7 | Strong financing capacity | |
| CSF-O-8 | Effective organizing and planning | |
| CSF-O-9 | Company references | |
| CSF-O-10 | Company experience in selected market | |
| External factors | CSF-E-1 | Economic conditions in the host country |
| CSF-E-2 | Financial conditions in the host country | |
| CSF-E-3 | Regularity of construction market | |
| CSF-E-4 | Level of competition in the host country | |
| CSF-E-5 | Legislation in the host country | |
| CSF-E-6 | Public procurement system in the host country | |
| CSF-E-7 | Investor | |
| CSF-E-8 | Existence of a foreign partner | |
| CSF-E-9 | Local construction companies/subcontractors | |
CSF group ranking
| Generic group of CSFs | s-factor |
|---|---|
| Project-related factors | 67.7 |
| Human-related factors | 66.8 |
| Organizational factors | 70.8 |
| External factors | 71.9 |
j_otmcj-2021-0030_tab_010
| Group of CSFs | Code | Skewness | Kurtosis | ||
|---|---|---|---|---|---|
| Statistic | Stand. Error | Statistic | Stand. Error | ||
| Project-related factors | CSF-P-1 | 3.00 | 1.26 | 60.0 | 9 |
| CSF-P-2 | 4.11 | 0.98 | 82.3 | 1 | |
| CSF-P-3 | 3.54 | 0.87 | 70.9 | 2 | |
| CSF-P-4 | 3.54 | 0.81 | 70.9 | 3 | |
| CSF-P-5 | 3.03 | 1.11 | 60.6 | 8 | |
| CSF-P-6 | 3.37 | 0.93 | 67.4 | 7 | |
| CSF-P-7 | 3.46 | 1.27 | 69.1 | 6 | |
| CSF-P-8 | 2.74 | 0.94 | 54.9 | 10 | |
| CSF-P-9 | 3.54 | 0.91 | 70.9 | 4 | |
| CSF-P-10 | 3.49 | 1.34 | 69.7 | 5 | |
| Human-related factors | CSF-H-1 | 3.46 | 0.97 | 78.3 | 1 |
| CSF-H-2 | 3.66 | 1.24 | 73.1 | 2 | |
| CSF-H-3 | 3.40 | 1.13 | 68.0 | 4 | |
| CSF-H-4 | 3.57 | 1.10 | 71.4 | 3 | |
| CSF-H-5 | 2.91 | 0.87 | 58.3 | 8 | |
| CSF-H-6 | 3.09 | 1.02 | 61.7 | 6 | |
| CSF-H-7 | 3.11 | 1.14 | 62.3 | 5 | |
| CSF-H-8 | 3.06 | 1.07 | 61.1 | 7 | |
| Organizational factors | CSF-O-1 | 3.71 | 1.21 | 74.3 | 2 |
| CSF-O-2 | 3.34 | 1.07 | 66.9 | 9 | |
| CSF-O-3 | 3.23 | 0.90 | 64.6 | 10 | |
| CSF-O-4 | 3.71 | 0.97 | 74.3 | 3 | |
| CSF-O-5 | 3.43 | 1.15 | 68.6 | 8 | |
| CSF-O-6 | 3.46 | 0.81 | 69.1 | 6 | |
| CSF-O-7 | 3.63 | 1.12 | 72.6 | 5 | |
| CSF-O-8 | 3.74 | 0.87 | 74.9 | 1 | |
| CSF-O-9 | 3.69 | 1.43 | 73.7 | 4 | |
| CSF-O-10 | 3.46 | 0.84 | 69.1 | 7 | |
| External factors | CSF-E-1 | 3.37 | 0.76 | 67.4 | 7 |
| CSF-E-2 | 3.49 | 0.73 | 69.7 | 6 | |
| CSF-E-3 | 3.54 | 0.84 | 70.9 | 5 | |
| CSF-E-4 | 3.37 | 0.93 | 67.4 | 8 | |
| CSF-E-5 | 3.69 | 0.89 | 73.7 | 4 | |
| CSF-E-6 | 2.94 | 1.17 | 58.9 | 9 | |
| CSF-E-7 | 4.00 | 1.01 | 80.0 | 2 | |
| CSF-E-8 | 3.89 | 0.82 | 78.9 | 3 | |
| CSF-E-9 | 4.03 | 1.08 | 80.6 | 1 | |
Ranking of CSFs related to the success of ICPs
| Group of CSFs | Code | Mean | SD | s-factor | Group rank | Overall rank |
|---|---|---|---|---|---|---|
| Project-related factors | CSF-P-1 | 3.00 | 1.26 | 60.0 | 9 | 34 |
| CSF-P-2 | 4.11 | 0.98 | 82.3 | 1 | 1 | |
| CSF-P-3 | 3.54 | 0.87 | 70.9 | 2 | 14 | |
| CSF-P-4 | 3.54 | 0.81 | 70.9 | 3 | 15 | |
| CSF-P-5 | 3.03 | 1.11 | 60.6 | 8 | 33 | |
| CSF-P-6 | 3.37 | 0.93 | 67.4 | 7 | 25 | |
| CSF-P-7 | 3.46 | 1.27 | 69.1 | 6 | 20 | |
| CSF-P-8 | 2.74 | 0.94 | 54.9 | 10 | 37 | |
| CSF-P-9 | 3.54 | 0.91 | 70.9 | 4 | 16 | |
| CSF-P-10 | 3.49 | 1.34 | 69.7 | 5 | 18 | |
| Human-related factors | CSF-H-1 | 3.46 | 0.97 | 78.3 | 1 | 5 |
| CSF-H-2 | 3.66 | 1.24 | 73.1 | 2 | 11 | |
| CSF-H-3 | 3.40 | 1.13 | 68.0 | 4 | 24 | |
| CSF-H-4 | 3.57 | 1.10 | 71.4 | 3 | 13 | |
| CSF-H-5 | 2.91 | 0.87 | 58.3 | 8 | 36 | |
| CSF-H-6 | 3.09 | 1.02 | 61.7 | 6 | 31 | |
| CSF-H-7 | 3.11 | 1.14 | 62.3 | 5 | 30 | |
| CSF-H-8 | 3.06 | 1.07 | 61.1 | 7 | 32 | |
| Organizational factors | CSF-O-1 | 3.71 | 1.21 | 74.3 | 2 | 7 |
| CSF-O-2 | 3.34 | 1.07 | 66.9 | 9 | 28 | |
| CSF-O-3 | 3.23 | 0.90 | 64.6 | 10 | 29 | |
| CSF-O-4 | 3.71 | 0.97 | 74.3 | 3 | 8 | |
| CSF-O-5 | 3.43 | 1.15 | 68.6 | 8 | 23 | |
| CSF-O-6 | 3.46 | 0.81 | 69.1 | 6 | 21 | |
| CSF-O-7 | 3.63 | 1.12 | 72.6 | 5 | 12 | |
| CSF-O-8 | 3.74 | 0.87 | 74.9 | 1 | 6 | |
| CSF-O-9 | 3.69 | 1.43 | 73.7 | 4 | 9 | |
| CSF-O-10 | 3.46 | 0.84 | 69.1 | 7 | 22 | |
| External factors | CSF-E-1 | 3.37 | 0.76 | 67.4 | 7 | 26 |
| CSF-E-2 | 3.49 | 0.73 | 69.7 | 6 | 19 | |
| CSF-E-3 | 3.54 | 0.84 | 70.9 | 5 | 17 | |
| CSF-E-4 | 3.37 | 0.93 | 67.4 | 8 | 27 | |
| CSF-E-5 | 3.69 | 0.89 | 73.7 | 4 | 10 | |
| CSF-E-6 | 2.94 | 1.17 | 58.9 | 9 | 35 | |
| CSF-E-7 | 4.00 | 1.01 | 80.0 | 2 | 3 | |
| CSF-E-8 | 3.89 | 0.82 | 78.9 | 3 | 4 | |
| CSF-E-9 | 4.03 | 1.08 | 80.6 | 1 | 2 | |
j_otmcj-2021-0030_tab_009
| Generic group of CSFs | Statistic | df | Sig. |
|---|---|---|---|
| Project-related factors | 0.942 | 34 | 0.070 |
| Human-related factors | 0.971 | 34 | 0.498 |
| Organizational factors | 0.940 | 34 | 0.094 |
| External factors | 0.959 | 34 | 0.234 |
Profile of the respondents
| Variables | Frequency | Percentage (%) |
|---|---|---|
| Company role | ||
| Constructor | 26 | 74.3 |
| Consultant | 9 | 25.7 |
| Company type | ||
| Small | 16 | 45.7 |
| Medium | 5 | 14.3 |
| Large | 14 | 40.0 |
| International experience (years) | ||
| <5 | 5 | 14.3 |
| 5–10 | 7 | 20.0 |
| 10–20 | 10 | 28.6 |
| 20 | 13 | 37.1 |
| Number of ICPs | ||
| <10 | 8 | 22.9 |
| 10–20 | 18 | 51.4 |
| 20 | 9 | 25.7 |
| Type of ICP | ||
| Private | 8 | 22.9 |
| Public | 23 | 65.7 |
| PPP | 4 | 11.4 |
| Location of ICP | ||
| EU members | 10 | 28.6 |
| Non EU members | 16 | 45.7 |
| Africa | 5 | 14.3 |
| Asia | 4 | 11.4 |
j_otmcj-2021-0030_tab_008
| Generic group of CSFs | Cronbach's alpha | No. of items |
|---|---|---|
| Project-related factors | 0.966 | 10 |
| Human-related factors | 0.979 | 8 |
| Organizational factors | 0.961 | 10 |
| External factors | 0.945 | 9 |
j_otmcj-2021-0030_tab_007
| CSF indicators | Not critical (%) | Potentially critical (%) | Critical (%) | |
|---|---|---|---|---|
| Project-related factors | ||||
| 1 | Project size and value | 10 | 70 | 20 |
| 2 | Project characteristics/Uniqueness of project activities | 40 | 30 | 30 |
| 3 | Constructability/Complexity | 30 | 10 | 60 |
| 4 | Site management | 30 | 50 | 20 |
| 5 | Accurate initial cost estimates | 30 | 10 | 60 |
| 6 | Formal dispute resolution process | 20 | 70 | 10 |
| 7 | Adequate funding throughout the project | 20 | 30 | 50 |
| 8 | Effective project planning and control | 20 | 70 | 10 |
| 9 | IT support for project management | 40 | 50 | 10 |
| 10 | Language barriers | 60 | 40 | |
| 11 | Appropriate project identification | 10 | 40 | 50 |
| 12 | Effective project management | 20 | 20 | 60 |
| 13 | Completion of the project on time | 20 | 40 | 40 |
| 14 | Quality of the work | 30 | 40 | 30 |
| 15 | Innovative technical approaches | 40 | 30 | 30 |
| Human-related factors | ||||
| 16 | Organizing skills of project manager | 40 | 30 | 30 |
| 17 | Coordinating ability of project manager | 40 | 20 | 40 |
| 18 | Project manager's competency | 40 | 10 | 50 |
| 19 | Communication skills of project manager | 50 | 20 | 30 |
| 20 | Project manager's experience | 40 | 60 | |
| 21 | Education level of the project manager | 40 | 20 | 40 |
| 22 | Political connections of the project manager | 10 | 40 | 10 |
| 23 | Decision-making ability of project manager | 40 | 10 | 50 |
| 24 | Leadership skills of project manager | 30 | 20 | 50 |
| 25 | Motivating skills of project manager | 40 | 30 | 30 |
| 26 | Project manager's adaptability to changes in project plan | 20 | 60 | 20 |
| 27 | Project manager's ability for risk identification | 20 | 40 | 40 |
| 28 | Technical background of project team members | 30 | 40 | 30 |
| 29 | Communication skills of project team members | 40 | 30 | 30 |
| 30 | Commitment | 30 | 20 | 50 |
| 31 | Troubleshooting skills of project team members (problem-solving) | 30 | 50 | 20 |
| 32 | Effective relationship among project team members | 30 | 40 | 30 |
| 33 | Multidisciplinary team | 40 | 10 | 50 |
| 34 | Multinational team | 50 | 30 | 20 |
| Organizational factors | ||||
| 35 | Top management support | 30 | 20 | 50 |
| 36 | Organizational structure | 60 | 30 | 10 |
| 37 | Functional managers support | 50 | 40 | 10 |
| 38 | Company's flexibility | 30 | 50 | 20 |
| 39 | Good business/government relationships | 60 | 20 | 20 |
| 40 | Comprehensive contract documentation | 70 | 30 | |
| 41 | Quality control | 20 | 30 | 50 |
| 42 | Effective project monitoring and control | 40 | 40 | 20 |
| 43 | Clear goals and objectives | 10 | 60 | 30 |
| 44 | Control of cash-flow | 40 | 40 | 20 |
| 45 | Strong financing capacity | 20 | 20 | 60 |
| 46 | Effective organizing and planning | 20 | 60 | 20 |
| 47 | Risk management | 10 | 60 | 30 |
| 48 | Follow and adopt new technologies | 60 | 40 | |
| 49 | Skillful workers | 40 | 40 | 20 |
| 50 | Cost management | 40 | 40 | 20 |
| External factors | ||||
| 51 | Economic and politic environment | 30 | 50 | 20 |
| 52 | Financial environment | 30 | 20 | 50 |
| 53 | Regularity of construction market and legislation | 30 | 50 | 20 |
| 54 | Level of competition | 30 | 50 | 20 |
| 55 | Company experience in selected market | 20 | 30 | 50 |
| 56 | Competitive tendering system in selected market | 50 | 30 | 20 |
CSFs indicators for the success of ICPs identified from relevant literature
| CSF indicators | Author(s) | |
|---|---|---|
| Project-related factors | ||
| 1 | Project size and value | Belassi and Tukel 1996; Chan et al. 2004; Fortune and White 2006; Arain and Asif 2010; Khan and Spang 2011; Gudienė et al. 2014, Inayat et al. 2015; Alashwal et al. 2017; Shen et al. 2017; Mavi and Standing 2018; Mathar et al. 2020 |
| 2 | Project characteristics/Uniqueness of project activities | Belassi and Tukel 1996; Chen et al. 2012, Gudienė et al. 2014 |
| 3 | Constructability/Complexity | Saqib et al. 2008; Arain and Asif 2010; Yong and Mustaffa 2013, Gudienė et al. 2014; Mavi and Standing 2018; Mathar et al. 2020 |
| 4 | Site management | Arain and Asif 2010; Yong and Mustaffa 2013; Ghanbaripour et al. 2020, Mathar et al. 2020 |
| 5 | Accurate initial cost estimates | Nguyen et al. 2004; Arain and Asif 2010 |
| 6 | Formal dispute resolution process | Saqib et al. 2008; Arain and Asif 2010; Pal et al. 2017; Mathar et al. 2020 |
| 7 | Adequate funding throughout the project | Nguyen et al. 2004; Fortune and White 2006; Arain and Asif 2010; Yong and Mustaffa 2013; Gudienė et al. 2014; Li et al. 2019; Ghanbaripour et al. 2020 |
| 8 | Effective project planning and control | Chan et al. 2004; Nguyen et al. 2004; Saqib et al. 2008; Fortune and White 2006; Toor and Ogunlana 2009; Arain and Asif 2010; Gudienė et al. 2014, Mavi and Standing 2018; Li et al. 2019 |
| 9 | IT support for project management | Pandit and Zhu 2007; Toor and Ogunlana 2009; Mathar et al. 2020 |
| 10 | Language barriers | Belassi and Tukel 1996 |
| 11 | Appropriate project identification | Qiao et al. 2001 |
| 12 | Effective project management | Belassi and Tukel 1996 |
| 13 | Completion of the project on time | Belassi and Tukel 1996 |
| 14 | Quality of the work | Belassi and Tukel 1996 |
| 15 | Innovative technical approaches | Belassi and Tukel 1996; Khan and Spang 2011; Gudienė et al. 2014; Shen et al. 2017; Li et al. 2019 |
| Human-related factors | ||
| 16 | Organizing skills of project manager | Saqib et al. 2008; Gudienė et al. 2014; Alashwal et al. 2017 |
| 17 | Coordinating ability of project manager | Belassi and Tukel 1996; Chan et al. 2004; Saqib et al. 2008; Gudienė et al. 2014 |
| 18 | Project manager's competency | Belassi and Tukel 1996; Chan et al. 2004; Nguyen et al. 2004; Fortune and White 2006; Saqib et al. 2008; Khan and Spang 2011; Yong and Mustaffa 2013; Gudienė et al. 2014; Bayiley and Teklu 2016; Alashwal et al. 2017; Banihashemi et al. 2017; Shen et al. 2017; Mavi and Standing 2018; Li et al. 2019; Ghanbaripour et al. 2020; Mathar et al. 2020 |
| 19 | Communication skills of project manager | Arslan and Kivrak 2008; Gudienė et al. 2014 |
| 20 | Project manager's experience | Ogunlana et al. 2002; Fortune and White 2006; Pheng and Chuan 2006; Saqib et al. 2008; Gudienė et al. 2014 |
| 21 | Education level of the project manager | Arslan and Kivrak 2008 |
| 22 | Political connections of the project manager | Arslan and Kivrak 2008 |
| 23 | Decision-making ability of project manager | Saqib et al. 2008 |
| 24 | Leadership skills of project manager | Arslan and Kivrak 2008; Saqib et al. 2008; Yong and Mustaffa 2013; Gudienė et al. 2014 |
| 25 | Motivating skills of project manager | Chan et al. 2004; Saqib et al. 2008; Gudienė et al. 2014 |
| 26 | Project manager's adaptability to changes in the project plan | Saqib et al. 2008; Yong and Mustaffa 2013; Gudienė et al. 2014; Banihashemi et al. 2017 |
| 27 | Project manager's ability for risk identification | Gudienė et al. 2014; Banihashemi et al. 2017 |
| 28 | Technical background of project team members | Belassi and Tukel 1996; Gudienė et al. 2014; Alashwal et al. 2017; Mathar et al. 2020 |
| 29 | Communication skills of project team members | Belassi and Tukel 1996; Ofori 2003; Gudienė et al. 2014; Alashwal et al. 2017; Shen et al. 2017 |
| 30 | Commitment | Belassi and Tukel 1996; Arain and Asif 2010; Khan and Spang 2011; Alashwal et al. 2017; Mavi and Standing 2018; Mathar et al. 2020 |
| 31 | Troubleshooting skills of project team members (problem-solving) | Belassi and Tukel 1996; Saqib et al. 2008; Gudienė et al. 2014; Liu et al. 2016; Alashwal et al. 2017; Pal et al. 2017 |
| 32 | Effective relationship among project team members | Arslan and Kivrak 2008; Liu et al. 2016; Banihashemi et al. 2017 |
| 33 | Multidisciplinary team | Qiao et al. 2001; Nguyen et al. 2004; Ghanbaripour et al. 2020 |
| 34 | Multinational team | Qiao et al. 2001 |
| Organizational factors | ||
| 35 | Top management support | Belassi and Tukel 1996; Cooke-Davies 2002; Ofori 2003; Nguyen et al. 2004; Toor and Ogunlana 2009; Khan and Spang 2011; Yong and Mustaffa 2013; Liu et al. 2016; Alashwal et al. 2017; Mavi and Standing 2018; Li et al. 2019; Ghanbaripour et al. 2020 |
| 36 | Organizational structure | Belassi and Tukel 1996; Fortune and White 2006; Saqib et al. 2008; Khan and Spang 2011; Banihashemi et al. 2017; Mavi and Standing 2018 |
| 37 | Functional managers support | Belassi and Tukel 1996 |
| 38 | Company's flexibility | Arain and Asif 2010 |
| 39 | Good business/government relationships | Qiao et al. 2001; Arain and Asif 2010 |
| 40 | Comprehensive contract documentation | Nguyen et al. 2004; Arain and Asif 2010; Yong and Mustaffa 2013; Banihashemi et al. 2017; Ahmadabadi and Heravi 2019 |
| 41 | Quality control | Qiao et al. 2001; Saqib et al. 2008; Arain and Asif 2010; Mathar et al. 2020 |
| 42 | Effective project monitoring and control | Kwak 2002; Ofori 2003; Arslan and Kivrak 2008; Arain and Asif 2010; Khan and Spang 2011; Mavi and Standing 2018; Mathar et al. 2020 |
| 43 | Clear goals and objectives | Ofori 2003; Nguyen et al. 2004; Fortune and White 2006; Arain and Asif 2010; Mavi and Standing 2018; Li et al. 2019; Mathar et al. 2020 |
| 44 | Control of cash-flow | Arslan and Kivrak 2008; Mathar et al. 2020 |
| 45 | Strong financing capacity | Arslan and Kivrak 2008; Alashwal et al. 2017; Ghanbaripour et al. 2020 |
| 46 | Effective organizing and planning | Nguyen et al. 2004; Arslan and Kivrak 2008; Arain and Asif 2010; Banihashemi et al. 2017; Mathar et al. 2020 |
| 47 | Risk management | Arslan and Kivrak 2008; Saqib et al. 2008; Khan and Spang 2011; Mavi and Standing 2018; Li et al. 2019; Mathar et al. 2020 |
| 48 | Follow and adopt new technologies | Ofori 2003; Arslan and Kivrak 2008; Chen et al. 2012 |
| 49 | Skillful workers | Arslan and Kivrak 2008; Yong and Mustaffa 2013; Alashwal et al. 2017 |
| 50 | Cost management | Ofori 2003; Arslan and Kivrak 2008; Yong and Mustaffa 2013 |
| External factors | ||
| 51 | Economic and politic environment | Belassi and Tukel 1996; Qiao et al. 2001; Kwak 2002; Chan et al. 2004; Saqib et al. 2008; Khan and Spang 2011; Yong and Mustaffa 2013; Alashwal et al. 2017; Banihashemi et al. 2017; Shen et al. 2017; Mavi and Standing 2018; Razzaq et al. 2018; Ahmadabadi and Heravi 2019 |
| 52 | Financial environment | Qiao et al. 2001; Alashwal et al. 2017; Mavi and Standing 2018; Ahmadabadi and Heravi 2019 |
| 53 | Regularity of construction market and legislation | Qiao et al. 2001; Kwak 2002; Bayiley and Teklu 2016; Mavi and Standing 2018; Razzaq et al. 2018 |
| 54 | Level of competition | Belassi and Tukel 1996; Arslan and Kivrak 2008; Yong and Mustaffa 2013 |
| 55 | Company experience in selected market | Arslan and Kivrak 2008; Yong and Mustaffa 2013; Surlan et al. 2016; Mathar et al. 2020 |
| 56 | Competitive tendering system in selected market | Qiao et al. 2001; Chen et al. 2012; Yong and Mustaffa 2013 |