On returning value 1 when the utility of being prophylactic is greater than the utility of getting susceptible and 0 otherwise (see information in Behavioral Decision Model).METHODSThe SPIR modelThe SPIR model couples two sub-models: 1, the Illness Dynamics Model, reproducing the dynamics from the infectious illness, and an additional, the Behavioral Selection Model, that determines how agents in the illness dynamics model make the decision to engage in prophylactic or non-prophylactic behavior.Disease dynamics model The disease dynamics model reproduces the dynamics in the infectious disease inside a constant population of N agents. Every agent might be in a single of 4 states: Susceptible (S), Prophylactic (P), Infectious (I), or Recovered (R). The difference in between agents in states S and P is the fact that the former engage in non-prophylactic behavior and don’t implement any measure to stop infection, whilst the latter adopt prophylactic behavior which decreases their probability of being infected (e.g., wearing a mask, washing hands, and so on.). The adoption of prophylactic behavior, on the other hand, imposes expenses on people that may well protect against them from engaging in such behavior. In Western nations, for instance, wearing a mask, apart from uncomfortable, might signal a lack of trust in others or an unhealthy state, therefore reducing social contacts. Agents in the infectious state I are infected and infective, whilst these in the recovered state R are immune to and do not transmit disease. The transition in between states is captured using the state-transition diagram shown in Fig. 1. For reference, all the parameters and variables within the SPIR model are listed and defined in Table 1. This sub-model assumes that in each time step, 3 sorts of events happen: (1) interactions among agents and any infections that may possibly result, (2) behavioral decisionsNardin et al. (2016), PeerJ, DOI 10.7717/peerj.3/Table 1 Parameters and state variables with the SPIR model. Symbol N S P I R s p i r bS bP Definition Total quantity of agents in the population. An agent in the susceptible state engaging in nonprophylactic behavior. An agent in the prophylactic state engaging in prophylactic behavior. An agent within the infectious state. An agent inside the recovered state. Proportion of susceptible agents in the PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/20011050 population. Proportion of prophylactic agents within the population. Proportion of infectious agents inside the population. Proportion of recovered agents within the population. Probability that an agent inside the susceptible state becomes infected upon interacting with an infectious agent. Probability that an agent within the prophylactic state becomes infected upon interacting with an infectious agent. Reduction within the transmission probability or rate when adopting prophylactic behavior: bP = bS (0 1). Note that we refer to 1 – as the protection. Probability an infectious agent recovers. Probability an agent in the susceptible or prophylactic state decides which behavior to engage in. Distortion on the perceived proportion of infectious agents within the population (i.e., distortion issue). Payoff per time step for becoming in state Y, exactly where Y S,P,I,R. Note that (uS – uP ) is BI-7273 definitely the cost of adopting prophylactic behavior. Quantity of time actions agents count on to commit in state Y assuming they decide to adopt state X (i.e., DX ), where Y S,P,I,R and X S,P. Utility for adopting state X, exactly where X S,P. In area A, agents never adopt prophylactic behavior. In region B, agents adopt prophylactic behavior above the reported.
