# Assessing and Priorities Delay Factors of Prefabricated Concrete Building Projects in China
## 5 Results and Analysis
### DEMATEL Analysis
In China, some construction workers may lack the systematic and professional training for assembly techniques in prefabricated projects because of the cost of training courses. Consequently, construction workers lack the insight into potential issues due to little experience in tackling the existing difficulties. Such insufficient proficiency inevitably leads to low productivity and time-consuming procedures in structural connections for prefabricated components. However, Factor 67, 'inefficient structural connections', with an \(r\)-value of 0.1752 has a low probability for influencing other factors. In terms of the received-influence value in the eighth column of Table 5, the delay factors can be ranked in the following order: F67, F42, F22, F31, F66, F69, F63, F62, F32, F61, F64, F51, F13, F12, F23, F68, F11, F41, F65, F52, F21, F72, F73, and F71. Factor 67, 'inefficient structural connections', is the most easily affected by the most delay factors, especially 'low-precision installation techniques' (F11), 'inadequate worker experience' (F21), and most contractor-related factors. Apart from F67,'vehicle and equipment unavailability' (F42), 'low productivity' (F22),'shortage and delay in material supply' (F31), and'rehandling components' (F66) are also very easily affected by the other investigated factors. A causal diagram is plotted as presented in Figure 3 in terms of the datasets of \(r+c\) and \(r-c\), which are provided in Table 5.  
Figure 3: Causal diagram for delay factors in prefabricated construction. According to the x-axis values, the delay factors can be ranked in the following order: F67, F22, F66, F42, F61, F64, F31, F21, F63, F65, F62, F13, F69, F23, F32, F12, F11, F51, F41, F72, F68, F73, F52, and F71. 'Inefficient structural connections' (F67) is identified as the most import factor as it demonstrates the highest level of interrelationship with other factors. Apart from F67, the figure indicates other core issues for solving the delay problem of prefabricated construction projects, such as 'low productivity' (F22),'rehandling components' (F66),'vehicle and equipment unavailability' (F42), 'improper construction planning and schedule design' (F61), and 'lack of communication among participants' (F64). As presented in Figure 3, the investigated delay factors are divided into two cause-and-effect clusters. The effect cluster comprises F51, F62, F32, F69, F66, F22, F42, F31, and F67 owing to negative values of \(r-c\). Other factors, including F21, F65, F64, F61, F23, F11, F41, F72, F73, F71, F52, F63, and F68, are included in the cause cluster owing to positive value of \(r-c\). The cause-and-effect clusters indicate that eliminating the effects from effect factors can effectively improve the project schedule performance. The solution could be to determine their corresponding cause factors in order to determine mitigation measures. In particular, Factor 21, 'inadequate worker experience', is considered the highest causal factor while Factor 67, 'inefficient structural connections', is the highest effect factor in terms of their y-axis values. Thus, F21 has the most significant impact on the other factors. Avoiding F21 is able to greatly decrease the likelihoods of cause factors occurring for improving the schedule performance.