# Day and Night: Locating the General Practitioner's Panel after Hours
## 4 Discussion
### Future Research  
This case study indicates that the simultaneous approach is an effective method of addressing both the regular and after-hours time settings when considering practical facility location constraints. However, there are other considerations when addressing this problem that should be considered in future work. These points are outside of the scope of this research but may be important to consider in the context of developing real-world policy for primary care resource allocation. Firstly, the p-Median problem was determined to be an appropriate OR model for demonstrating the merits of considering multiple time settings simultaneously. Particularly since the case studies cover populations with varying densities, the objective of the p-Median to minimise all distance travelled is desirable when compared with the other models that were considered. In other contexts, the p-center problem, the location set covering problem (LSCP), or the maximum covering location problem (MCLP) may be more appropriate [15; 16; 17]. Respectively, the objectives of these models are to minimise the greatest distance travelled by any customer, to minimise the number of facilities needed to cover a population (coverage meaning ensuring no one from the population is further than a specified distance), and to maximise the number of customers within a specific distance of a facility. These models are compatible with the simultaneous approach to treating the regular and after-hours settings, and there may be scenarios where these are more appropriate than the p-Median problem. It may also be of interest to use different models in different time settings for unique objectives. For example, the p-Median could be more appropriate during regular hours when there are more facilities available, but if there are only a small number of after-hours facilities, the LSCP might be better able to maximise the number of people who have access to a facility if they need it. This would provide a solution where regular facilities provide an optimal solution for the average patient, and the number of people who are far from after-hours facilities would be minimised. The p-center problem may be of particular interest for improving accessibility in rural areas since it provides an equitable solution by reducing the greatest distances travelled. Another potential adjustment to the models used for primary care facility location is to incorporate capacitated facilities. The models in this work have no specific regard for capacity; that is, the PCPs may be considered to have larger or smaller panel sizes than individual GPs typically have. However, this may still accurately reflect clinics where multiple GPs share a space, thus collectively treating more patients within the same facility. Many GPs prefer to work in practices with several other physicians, and realistically, this is the case for many PCPs. Rather than placing individual facilities with no regard for capacity, a model which places facilities with multiple GPs that can handle a constrained panel range may yield more insight into facility location strategies which strictly satisfy physician preferences. It may also be appropriate to relax facility location constraints and instead add facility costs to control the number of facilities opened. While it is clear that adding more facilitieswill always allow for solutions with lower distances between demand and facilities, this does not account for the economic costs of additional facilities. A multi-criteria decision analysis may help determine the cost-effectiveness of the number of facilities available. Since the marginal improvement in patient distance travelled decreases as the number of facilities increases, this suggests that there is a point where the gains in accessibility are outweighed by the additional facility costs. A model which replaces facility location constraints with facility costs may also provide more effective solutions for both the regular and after-hours.