4.4.2. Case-Based Reasoning

From the 12 studies implementing CBR to model the costs of building projects, only Kim et al. [72] conducted a comparison with a different technique—ANN. The 11 other papers shown in Table 6 presented attribute weight and case similarity measures as the primary concern at the time of developing improvements in CBR, utilising GA and MRA to assign the optimum weight of the attributes.


**Table 6.** Improvements on CBR models from studies.

#### 4.4.3. Multiple-Regression Analysis

The use of multiple-regression analysis as a primary technique was utilised in 10 of the 46 articles. Five of them did not create additional models to compare results. Sonmez [55] and Dursun and Stoy [73] compared their accuracy with models developed with ANN, and Li et al. [74] compared an MRA model with the Unit Area Cost method. Lowe et al. [52] and Ji et al. [71] utilised techniques of Stepwise Regression and Principal Component Analysis to select the optimal parameters, respectively. Although MRA was not the most explored technique by the studies, it can support other techniques and enhance their effectiveness, e.g., it was used in CBR modelling to improve the adaptation capability [77]. Additionally, MRA is a technique more accessible for cost-estimation practitioners because it has broadly studied and implemented in statistics.
