Introduction to Model Building Presentation 1 of 6 of six week workshop that runs from January - February 2011

1. Web simulation development fundamentals using Forio Simulate Michael Bean Forio Business Simulations

5. A simulation is like a spreadsheet optimized for solving problems that occur over time

7. "It is a confusion of ideas to suppose that the economical use of fuel is equivalent to diminished consumption. The very contrary is the truth." Jevons argued that improvements in fuel efficiency tend to increase , rather than decrease , fuel use.

8. Energy Efficiency = Higher Productivity Higher Productivity = Lower Implicit Price Lower Implicit Price = Higher Demand

10. There are only five statement types in a Forio Simulate model: V is a Variable D is a Decision M is a Model-wide property P is a Property of a variable or decision R is a Range

11. A variable can be either a constant or an equation : V Initial Size = 17 V Average Size = Initial Size V Yearly Spending on Electricity = Price of kWh Electricity * Average Refrigerator Size * kWh Electricity Consumed per Cubic Foot

12. ABS - Absolute value CEILING - Round Up FLOOR - Round down ROUND - Round INT - Integer FRAC - Fractional part of a number MOD - Modulus SAFEDIV0 - Return 0 if divisor is 0 MAX - Maximum value MIN - Minimum vale IF - Conditional REMEMBER - Store value when condition is true LOOKUP – Look up a value from a list HIVAL - Finds the highest value during a sim run LOVAL - Finds the lowest value during a sim run PREVIOUS - The value from the previous step STEP = Current Step (always starts at 0) TIME = Current Time RAND - Uniform random number RANDBETWEEN - Random number between two values NORMAL - Normally distributed random number EXPRND - Exponential distribution random number LOGNORMAL - Log-normal distribution POISSON - Poisson distribution Sample functions that work in Forio Simulate

13. A decision is a number that the user of the simulation can enter or change: D kWh Electricity Consumed per Cubic Foot = 1239 / Initial Refrigerator Size D Price of kWh Electricity = 0.11

15. Model-wide properties set the default properties for all variables and decisions: M StartTime = 2010 M EndTime = 2020 M InitialSteps = 2 M ExecuteDecisionImmediately = TRUE M NumberFormat = #,##0.00

18. Single biggest mistake that new modelers make: Writing too many equations before testing. You should test your model in the model explorer after every one or two new equations or model changes.

19. Challenges for the coming week Try extending this model to include a third array element such as a dishwasher. Try to include the price per kWh into the refrigerator size calculation. Start on your own model.

20. What’s next? Advanced array functions State functions Games versus planning tools Locating and solving model errors We’ll continue building our model of Jevon’s paradox.