Superdiffuser Model of Behavior Change in a Network

extensions [
  nw]

turtles-own [
  adopted?               ; whether or not the turtles have adopted the innovation
  pers-one               ; likelihood of an adopted turtle choosing link neighbor who has not adopted and trying to persuade them
  attitude               ; attitude towards adopting the behavior
  pers-power             ; how much a turtle adds to the attitude of another turtle if they target it
  adopt-friends          ; how many link neighbors have adopted, this is for the social influence variable
  non-adopt-friends      ; how many link neighbors have not adopted
  message ]              ; keeps track of message most recently received

globals [
   status-quo?           ; sets up the counter to count change for a stop condition
   status-quo-counter
  initial-degree  ;these next four are for the variables of the seeded agents
  initial-between
  initial-pers-power
  initial-pers-likely
  adopted-at-tick
  init-adopted2

]

to setup
  ca
  reset-ticks
  set status-quo? false
  set status-quo-counter 0                                                              ; for the stop code for no change in attitude
  nw:generate-preferential-attachment turtles links num-agents min-links                ; sets up preferential attachment network
  repeat 30 [ layout-spring turtles links 0.2 5 1 ]                                     ; makes the network look nicer

  ;new code assigning adoption
  ask turtles [set adopted? false]
  set init-adopted2 ((num-agents) * (percent-adopted-start))
  ask n-of init-adopted2 turtles [set adopted? true]

  ask turtles [
  set shape "person"
  set message 0
  set-pers-one
  set-attitude
  set-pers-power
  recolor]

  ;these four calculate the values for the seeded agents
  set initial-degree mean ( [ count link-neighbors ] of turtles with [ adopted? = true ] )
  set initial-between mean ( [ nw:betweenness-centrality ] of turtles with [ adopted? = true ] )
  set initial-pers-power mean [pers-power] of turtles with [adopted? = true]
  set initial-pers-likely mean [pers-one] of turtles with [adopted? = true]
  set adopted-at-tick count turtles with [adopted? = true]
end 

to set-pers-one ; turtle process
  set pers-one ( random-normal avg-pers-one 20 )      ; randomly assigns the the likelihood that a turtle will try to persuade another turtle at a tick
  if pers-one > 100 [ set pers-one 100 ]              ; the avg-pers-one slider sets the mean such that a higher setting means that more of the turtles will want to persuade
  if pers-one < 0 [ set pers-one 0 ]
end 

to set-attitude ; turtle process
  set attitude ( random-normal avg-attitude 1 )       ; sets up turtles' start attitude, below the lowest adoption threshold and at least 1 like a 1-7 likert scale
  if attitude > 3.9 [ set attitude 3.9 ]
  if attitude < 1.0 [ set attitude 1.0 ]
end 

to set-pers-power ; turtle process
  set pers-power ( random-normal avg-pers-power .1 )
  if pers-power > 2 [ set pers-power 2 ]
  if pers-power < 0 [ set pers-power 0 ]
end 

to recolor
  ifelse adopted? = true [
    set color red ] [
    set color white ]
end 

to update-friends ; turtle process
  set adopt-friends count link-neighbors with [ adopted? = true ]    ; updates number of adopted friends to use in the social influence calculation
  set non-adopt-friends count link-neighbors with [ adopted? = false ]
end 

;next 4 reporters are created to record values of agents seeded with adoption

to-report init-degree
  report initial-degree
end 

to-report init-between
  report initial-between
end 

to-report init-pers-power
  report initial-pers-power
end 

to-report init-pers-likely
  report initial-pers-likely
end 

;next four reporters report the agent values at each tick

to-report report-betweenness                                         ; creates the data for the monitor labeled betweenness centrality of adopted
  let adopted-betweenness mean ( [ nw:betweenness-centrality ] of turtles with [ adopted? = true ] )
  report adopted-betweenness
end 

to-report report-betweenness-all                                         ; creates the data for the monitor labeled betweenness centrality
  let betweenness-all mean ( [ nw:betweenness-centrality ] of turtles)
  report betweenness-all
end 

to-report report-degree                                              ; creates the data for the monitor labeled degree centrality of adopted
  let adopted-degree mean ( [ count link-neighbors ] of turtles with [ adopted? = true ] )
  report adopted-degree
end 

to-report report-degree-all                                             ; creates the data for the monitor labeled degree centrality
  let degree-all mean ( [ count link-neighbors ] of turtles)
  report degree-all
end 

to-report report-pers-power
  let adopt-pers-power mean [pers-power] of turtles with [adopted? = true]
  report adopt-pers-power
end 

to-report pers-likely-adopted
  let adopt-pers-likely mean [pers-one] of turtles with [adopted? = true]
  report adopt-pers-likely
end 

to-report global-clustering-coefficient
  let closed-triplets sum [ nw:clustering-coefficient * count my-links * (count my-links - 1) ] of turtles
  let triplets sum [ count my-links * (count my-links - 1) ] of turtles
  report closed-triplets / triplets
end 

to go
  let status-quo-before? status-quo?
  set status-quo? true
  ask turtles [
    update-friends                                             ; friends updated at the start of each tick
    if adopted? = true and non-adopt-friends > 0 [ persuade ]  ; persuasive attempts are only made by adopters
    if adopted? = false [ update-attitude ] ]                  ; attitude change only happens among non-adopters
  ifelse status-quo-before? = true and status-quo? = true [
    set status-quo-counter status-quo-counter + 1 ] [
    set status-quo-counter 0 ]
  tick
  if ticks < 1001 [set adopted-at-tick sentence (adopted-at-tick) (count turtles with [adopted? = true])]
  if status-quo-counter = 50 [ stop ]
  if ( not any? turtles with [ not adopted? ] ) [ stop ]     ; if the go is switched to run forever, it will stop if the whole network has adopted
end 

to persuade ; turtle process
  if ( random 100 < pers-one ) [
    ask one-of link-neighbors with [ adopted? = false ] [
      set message [ pers-power ] of myself ] ]               ; target will keep track of pers-power as message, to be used in update-attitude
end 

to update-attitude ; turtle process
  let old-attitude attitude                                               ; sets up the check for attitude changes this tick
  set attitude attitude + message + ( adopt-friends * social-influence )  ; attitude will change based on most recent message received AND social influence
  if attitude > 7 [
    set attitude 7 ]                                                      ; make sure attitude can't go over max for Likert scale
  if attitude >= adopt-threshold [ set adopted? true ]                    ; any turtle that reached the threshold will be set to adopted
  recolor                                                                 ; updates color based on adoption
  set message 0                                                           ; resets message variable to 0
  if old-attitude != attitude [ set status-quo? false ]                   ; indicates if there has been any attitude change this tick
end