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System Dynamics

Grape-leaf Hopper system

Lily Xia
A pest known as a grape-leaf hopper can cause considerable losses in vineyards. Periodically it was found that a natural parasite, anagrus epos, drastically reduced the size of the hopper population. This, in turn, led to a reduction in food (hoppers) available to the parasite and the parasite population declined until the hopper population increased again. This cycle would repeat.It was found that the parasite, anagrus epos, also feeds on a non-pest leaf hopper which feeds on blackberries. By planting small patches of wild blackberries in the vineyards, the growers were able to maintain a stable parasite population that was large enough to control population explosions of both leaf hoppers.

System Dynamics

  • 2 years 2 months ago

Clone of C difficile and Whole Genome Sequencing

InstructionsAdjust values by using the sliders below or typing in values, then press "Simulate"
To find total cases or total cost with or without WGS, run the simulation twice with WGS = 0 and WGS = 1 (make sure you record the values each time)
Refresh page to restore default values
Warning:Initial proportion of asymptomatically colonised patients + Initial proportion of symptomatically infected patients must be < 1
Proportion of admissions asymptomatically colonised + Proportion of admissions with symptomatic infection must be <1
Email with queries or comments

Healthcare HCAIs C Difficile System Dynamics

  • 6 years 1 month ago

Physician Workforce Model

Paulo Villela

Physician Workforce Model

Modelo baseado na Figura 1 do paper "Forecasting the need for medical specialists in Spain: application of a system dynamics model" (*) de Patricia Barber (**), Beatriz González López-Valcárcel.


(**) - University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de G.C., Canary Islands, Spain

Human Resources System Dynamics Human Health Service

  • 1 year 1 month ago

Rabbits and Snakes

Minh Nguyen
This model (starting with a clone of a previous project on squirrels, mountain lions, and hunters) is a simplified version using only rabbits and snakes.
By modifying the birth and death rates, the variations in population change dramatically. Interestingly, in this iteration, the populations reach dismal lows, but always pick up later. 

System Dynamics

  • 4 years 6 months ago

Clone of Sterman Model (2002)

Lou Morales
Based on model discussed by John D. Sterman (p 508) in All models are wrong: reflections on becoming a systems scientist (2002). Task: (A) Sketch what you think the resultant graph will be (see directions for drawing in model). (B) Then Run Simulation.  Optional Extension: Replace Graph In/Out Flow connection with a connection from Trig. function.  Repeat (A) & (B).

Sterman System Dynamics

  • 5 years 3 months ago