Sensitivity on RAMP slope

[trgzrich]

I have a model with a duration of 2000 to 2030. The baseline scenario is made under the assumption that the energy price
is introduced directly from data series from 2000 to 2009 and will keep at the level of 2009’s until 2030. After 2009, a
RAMP function is used. A sensitivity test on the slope of ramp function is needed to analyse future behaviour of
energy price growth. Assuming a random uniform distribution of the slope varying between 0.1 and 0.7, and simulated for
200 times.

How is this done, since energy price is not listed as a control parameter in the sensitivity simulation setup?

[bob@vensim.com]

You need to list the slope in the sensitivity simulation set up. This does need to be a parameter and not a constant embedded in an equation.

[trgzrich]

I first read the 2000-2009 energy price data using GET XLS DATA command, but l don't know how to add a RAMP function, to enable me carry out the sensitivity on the slope

[trgzrich]

I have this equation
ENERGY PRICE=GET XLS DATA('Energyprices.xls', 'Sheet1', '1', 'A2')

to get the 2000-2009 energy price data from the excel file. I would like to know how to use a RAMP function for the period after 2009, and thereafter conduct sensitivity tests on the slope.

[tomfid]

There are many ways to do this, depending on whether you want the ramp to override, or just modify the baseline energy price in your data. Two simple possibilities would be:

Energy Price Adj = ENERGY PRICE + RAMP(...)
&
Energy Price Adj = IF THEN ELSE( Time < energy price test time, ENERGY PRICE, energy price test )
energy price test = base energy price + RAMP(...)
energy price test time = 2009
...

The key is to make the parameters of your RAMP function and other inputs variables, rather than numbers, which permits sensitivity analysis and is also good practice for dimensional consistency.

[trgzrich]

Thanks very much Tom,
I think the first option is better for me. Do l need to enter this equation
Energy Price Adj = ENERGY PRICE + RAMP(...)
using "Add Eqn" in the equation editor for "ENERGY PRICE"?

This doesn't seem to work;
ENERGY PRICE=GET XLS DATA('ENERGYPRICES.xls', 'Sheet1', '1', 'A2') + Ramp(0.1,2010,2030)

How do l create the variable "Energy Price Adj"?

[bob@vensim.com]

You need 2 variables - use the Sketch Editor to add in the new variable and rearrange the connections.

[trgzrich]

Thank you very much!!!! It works.

[tomfid]

The "Add Eqn" option creates additional equations for subscripted variables - not what you need. - Tom