## 2 Literature Review and Hypothesis Development  
### Construction Supply Chain Integration (CSCI)  
In the strategic management literature, supply chain integration is categorized into two primary dimensions, i.e., vertical and horizontal integration. Vertical integration is defined as a competitive strategy by which a company takes complete control over one or more stages in the production or distribution of a product [26; 27]. Relatively, horizontal integration is defined as an acquisition strategy of a similar or a competitive business [28; 29]. Vertical integration considers both the transaction relationship and physical logistics, while the horizontal integration turns to the effectiveness and efficiency of capital [28; 29]. Strategic integration in the construction field focuses on vertical integration rather than horizontal integration [16; 30; 31] because the essence of vertical integration of a construction project related organization is to hold more parts of the whole supply chain. The dimensionality of supply chain integration is essential to reflect how the individual dimensions operate and function together [32]. One stream of supply chain integration literature investigated the vertical integration as a unidimensional construct [33; 34], while others divided it into internal and external dimensions [35]. Multiple dimensions come from various perspectives, e.g., flows of materials, information, and transactions/finances [36]. However, there is arguably a great deal of overlap or ambiguity among them, making it difficult to untangle their relationships. Thus, a topological approach from the focal organization to the extended supply chain is suggested for vertical integration dimensional development [27; 32]. Some research followed this logic and developed three integration dimensions of the general manufacturing supply chain: customer, supplier and internal integration [32; 37]. To extend the range of application to other peculiar supply chains, another stream literature redefined extended parts as forward integration (from the focal organization to the point of consumption) and backward integration (from the focal organization to the point of origin) [38; 39; 40]. In the construction supply chain, customer integration is limited to describing the downstream relationships, because the client (e.g., government) may not be the end-users (e.g., householders). Therefore, the expression of the forward integration is more appropriate for CSCI. Accordingly, this paper adopts the backward integration instead of the supplier integration. Under the requirements of the sustainability in construction, backward integration is vital to construct a visible, economical, and continuous material flow from off-site chains to on-site construction [41; 42]. Backward integration is concerned with the material flows from multi-levels of suppliers to the construction site, emphasizing the leading role of on-site construction activities and the supporting role of off-site upstream logistics [16; 41; 43; 44]. It is essential to adopt the backward integration to improve project-based focal construction organization, and further to elevate current project-based practices to supply chain management. [PERSON] and [PERSON] distinguished four specific practice paradigms of supply chain management in construction based on a series of case studies [41]: (1) improving the interface between the supply chain and the construction site; (2) improving the supply chain upstream; (3) transferring activities from the construction site to the supply chain; and (4) integrated management of the construction supply chain. These paradigms belong to the backward integration and are taken in this paper to measure the degree to which a focal construction organization takes measures with its upstream partners to guarantee and manage production, transportation, and construction activities. We redefine these descriptions of four paradigms and adapt them into observable variables.