title: Selecting the optimal healthcare centers with a modified P-median model: a visual analytic perspective.
abstract: BACKGROUND
  In a conventional P-median model, demanding points are likely assigned to the closest supplying facilities, but this method exhibits evident limitations in real cases.
  
  
  METHODS
  This paper proposed a modified P-median model in which exact and approximate strategies are used. The first strategy aims to enumerate all of the possible combinations of P facilities, and the second strategy adopts simulated annealing to allocate resources considering capacity constraint and spatial compactness constraint. These strategies allow us to choose optimal locations by applying visual analytics, which is rarely employed in location allocation planning.
  
  
  RESULTS
  This model is applied to a case study in Henan Province, China, where three optimal healthcare centers are selected from candidate cities. First, the weighting factor in spatial compactness constraint is visually evaluated to obtain a plausible spatial pattern. Second, three optimal healthcare centers, namely, Zhengzhou, Xinxiang, and Nanyang, are identified in a hybrid transportation network by performing visual analytics. Third, alternative healthcare centers are obtained in a road network and compared with the above solution to understand the impacts of transportation network types.
  
  
  CONCLUSIONS
  The optimal healthcare centers are visually detected by employing an improved P-median model, which considers both geographic accessibility and service quality. The optimal solutions are obtained in two transportation networks, which suggest high-speed railways and highways play a significant role respectively.
authors.forename: Tao
authors.initials: T
authors.lastname: Jia
authors.affiliation: Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, China. hhbtao@hust.edu.cn.
authors.forename: Hongbing
authors.initials: H
authors.lastname: Tao
authors.forename: Kun
authors.initials: K
authors.lastname: Qin
authors.forename: Yulong
authors.initials: Y
authors.lastname: Wang
authors.forename: Chengkun
authors.initials: C
authors.lastname: Liu
authors.forename: Qili
authors.initials: Q
authors.lastname: Gao
mesh_terms: D002681:China / Q000453:epidemiology; D003695:Delivery of Health Care / Q000379:methods* / Q000706:statistics & numerical data; D006297:Health Services Accessibility / Q000706:statistics & numerical data; D006801:Humans; D008962:Models, Theoretical; D062606:Tertiary Care Centers / Q000706:statistics & numerical data; D014186:Transportation / Q000379:methods* / Q000706:statistics & numerical data