| Title |
Model-Fit Analysis of the Public Design Fee Estimation System and Improvement Framework |
| DOI |
https://doi.org/10.5659/JAIK.2026.42.8.169 |
| Keywords |
Public Design Fee; Model Fit; Multiple Regression Analysis; Stage-Based Framework; Actual-Cost-Plus-Fixed-Fee Method; Design Service Contract Data |
| Abstract |
Public design fees in Korea function as institutional outputs shaped by budget logic, task scope, procurement, and contract conditions, yet
practice relies on construction-cost ratios that fail to capture actual workload and complexity. This study examines the gap between
budget-planning and contract-formation logic and proposes a stage-based framework from empirical evidence. Of 201 contracts, 87 valid cases
with complete records on contracted fee, construction cost, service type, fee method, duration, and procurement were analyzed via multiple
regression. The baseline model using only construction cost yielded R²=0.138, while the extended model with institutional variables yielded
R²=0.374. The actual-cost-plus-fixed-fee method (β=0.712, p=0.011) and comprehensive evaluation bidding (β=0.902, p=0.003) were significant,
while construction cost lost significance (p=0.272) once these variables were controlled, indicating that contracted fees are governed less by
cost magnitude than by procurement and fee structures. A three-stage system is thus proposed: at budget planning, construction cost and
facility type set preliminary fee bands adjusted for complexity and procurement; at design procurement, scope, BIM, permit burdens, and
manpower are reflected via a refined actual-cost-plus-fixed-fee method; at contract adjustment, added services from client changes or extended
duration are recorded and compensated, reframing design fees as multi-layered institutional outputs. |