 |
Download a pdf copy of this help file here |
|
Download a pdf copy of this help file here |
The ModelRisk Library provides the ability to organise your risk analysis work in three ways:
• Projects – organise models and simulation results by project
• Assumptions – store assumptions that you commonly use in your models
• References – organize references (files, web addresses) that are used in your models
One will frequently have several risk analysis models within an individual project. Each model will usually go through several different versions as the project develops, and for each model one might run several different analyses. The ModelRisk Library Projects tab is designed to help make organization of all these files much easier, and has the added benefit of providing a back-up facility in which you can quickly collate a project’s files into one folder and export.
Creating a project
One first
creates an assumption by clicking 
which opens the following dialog:
The project name appears in the left column of the Projects tab. The project description appears as a tool tip when one clicks on the project name:
Adding models to the project
In order for a model to be added to a project it must be loaded into Excel first. This is because ModelRisk will add some information to the Excel file in order to identify it with a project.
Once a model
has been loaded into Excel, select the project to which it is to be added
and click 
[Note: Models can be opened
in Excel without having to close the Library window.]. This will open
the following dialog:
One can enter any text for the model and description fields. On the right side one must select from among the models that are currently loaded into Excel. Click OK and the model is now added to the project:
Adding simulation results to the project
Once a model has been added to the project it can be loaded at any time into Excel by double-clicking the icon in the ModelRisk Library’s Projects tab.
One can then
run a simulation on the model and save the simulation results by adding
them to the Library by selecting the model and clicking 
.
The results are then displayed in the Library:
The saved simulation results can be retrieved at any time by double-clicking the Library entry, and does not require reloading of the model.
Adding different versions of a model to the project
Models usually go through an iterative process of development, where content is added or changed. It is good practice to save versions of the model as it progresses. It allows one to review the effect on results and to go back to previous versions where an error has occurred. New versions of a model are also often created to explore different scenarios.
ModelRisk allows one to save different versions of a model during its evolution. When you use a model that is already registered as part of the Library and make changes to it, on quitting the model ModelRisk will ask whether you wish to overwrite the registration in the Library or save it as a new version of the registered model.
Your company may have a number of assumptions that it wishes to be used across all models. For example, there might be an official company forecast of oil or steel prices, exchange rates or the cost of some product you manufacture. These official assumptions may be fixed values (deterministic) or include uncertainty (stochastic). The Assumptions tab within ModelRisk’s Library allows you to directly use these official assumptions within your model with a click of an icon. You can import any updates to the assumptions and future runs of your model will then be automatically updated.
Creating an assumption
One
first creates an assumption by clicking 
which
opens the following dialog:
The assumption name and description can be any text, but it is useful to bear in mind that the assumption list can be ordered alphabetically by either of these fields.
The assumption value can be a fixed value, for example:
2.87
1E8
27%
or a ModelRisk stochastic Object, for example:
=VoseNormalObject(2,3)
=VoseTimeGBMObject(0.02,0.1,100,)
=VoseCopulaMultiClaytonObject(10)
or simply some text, if required.
One can copy an html address into the ‘Assumption source’ field, in which case it will store the source as a hyperlink as shown for the second to fourth references in the screenshot above, or one can browse for a file location.
Clicking
OK then adds the assumption to the assumption list. Individual reference
can be deleted by selecting the appropriate row and clicking 
.
Assumptions can be edited by right-mouse clicking an entry and selecting ‘Edit this assumption’.
Adding an assumption to your model
Once an assumption has been incorporated into the library, it can be inserted into your spreadsheet model, as follows:
• Click on a spreadsheet cell
• Click the Library icon
• Select the Assumption tab and then the required assumption
•
Click the Insert button (or the 
icon if one wishes to put the reference in a different cell to the
one currently selected, or use the right-mouse click menu)
The formula in this cell now becomes:
=VoseLibAssumption("A0777432")
where ‘A0777432’ is replaced with the unique identification code for the assumption you have selected. The VoseLibAssumption function returns whatever value it has been assigned. Its purpose is to provide a direct link to the selected assumption. When browsing this cell with ModelRisk’s View Function tool, it will display as follows:
Clicking the VoseLibAssumption hyperlink will automatically open the Assumptions tab of the Library and select this assumption.
Clicking
the hyperlink entry in the Source column will directly open the web page
in your default browser. If the source is a file, clicking 
will open the file in the appropriate application.
You may have a number of references that you’ve used in quantifying the variables within your model, that refer to some theory you are using, or that are pertinent to your model in any number of ways. The Reference within ModelRisk’s Library tab allows you to store references to documents or html addresses. Using the VoseLibReference function a reference can then be attached to a cell of your model, allowing one to quickly review the reasons behind certain values or assumptions.
Creating a reference
One
first creates a reference by clicking 
which
opens the following dialog:
The reference name and description can be any text, but it is useful to bear in mind that the reference list can be ordered alphabetically by either of these fields.
On can copy an html address into the ‘Reference source’ field, in which case it will store the source as a hyperlink as shown for the first two references in the screen shot above, or one can browse for a file location.
ModelRisk
then adds the reference to the reference list. Individual reference can
be deleted by selecting the appropriate row and clicking 
.
Adding a reference to your model
Once a reference has been incorporated into the library, it can be inserted into your spreadsheet model. For example, imagine in some cell we have the formula:
=VosePoisson(127.4)
For someone not familiar with a Poisson distribution, we might want to point them to a particular reference. Reference #1 in the above list is the Wikipedia entry for the Poisson distribution. A reference entry can be inserted into Excel as follows:
• Click on the spreadsheet cell with the Poisson formula;
• Click the Library icon
• Select the References tab and then the required reference
•
Click the Insert button (or the 
icon if one wishes to put the reference in a different cell to the
one currently selected, or use the right-mouse click menu)
The formula in this cell now becomes:
=VosePoisson(127.4)+VoseLibReference("94D047C3")
The VoseLibReference function has no effect on the cells calculation: it returns a value of zero in the spreadsheet. Its purpose is to provide a direct link to the selected reference. When browsing this cell with ModelRisk’s View Function tool, it will display as follows:
Clicking the VoseLibReference hyperlink will automatically open the References tab of the Library and select this reference.
Clicking
the hyperlink entry in the Source column will directly open the web page
in your default browser. If the source is a file, clicking 
will open the file in the appropriate application.