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ModelAssist is a Wiki-style compilation of various theoretical and practical approaches used in quantitative risk analysis. It includes theory and equations, as well as example models, flow diagrams, quizzes and text to maximize your learning experience.  Example models are currently provided for two Excel simulation add-ins: Palisade's @RISK® and Oracle Crystal Ball®. However, you will see that the material applies to any simulation software, including analytical scripting languages such as R, Python, GNU Octave, Matlab, or Mathematica, and even for general-purpose languages such as C/C++/C# or JAVA


Navigation

The navigation panel on the left provides a hierarchical list of shortcuts to different topics that are arranged by category. This grouping presents a useful and thoughtful way of categorizing the material and provides users with all the information they need about what ModelAssist contains.
 

Some of the categories explain theoretical subjects such as ”Probability theory and statistics” and ”Analyzing and using data”, while the other categories concentrate on applied topics such as ”Project risk analysis”. 

The breadcrumbs links on the top of each page can also help you find the relative location/categorization of a specific page

 

The Search box  on the top right is a great way to find content. For example, a user could type, "approximate Binomial distribution" and receive a list of the pages that contain the relevant information. If you hit enter after entering a quick search, you will be taken to an advanced search page that will let you add filters and fine tune your search.  

 

If you want to find text within a specific page, go to the page, press CTRL-F, enter the search text, and hit ENTER.

Models

ModelAssist offers hundreds of models built in different simulation software packages. The models cover a broad range of techniques and fields. Each model is provided with a comprehensive explanation of any underpinning theory, and how and where it can be used. As there are different simulation software packages included in ModelAssist, make sure that you expand the model for the software package that you are studying. See an example below, using the Share Price Movement example model:

 Crystal Ball

  Exchange_rate

 

Here is a screenshot of the model:

 

Column C of the above model shows the value of sigma for each period, taking the value of 0.05 for the periods 1 to 99. For the following periods sigma will take values 0.05, 0.08 or 0.04 depending on the party that wins the election. The simulation of the election is shown in cell I17, which uses Crystal Ball's Custom distribution to construct a Discrete Distribution with values 1 (Conservative), 2 (Labour) and 3 (Liberal Democrats), and probabilities of success 25%, 70%, 5% respectively. Cell I18 looks up the value of sigma for the party that has won the election, which is then fed into column C.

 

Cell J19 shows the period of change in the exchange rate volatility if the Conservative party wins the election (an Integer Uniform distribution, constructed with Crystal Ball's Custom distribution). In addition, cell H25 checks if the Conservative party has won the election, and if it has, then returns either 1 or 0 with 50% probability each (using a Discrete Distribution, constructed with Crystal Ball's Custom distribution). Finally, the output column E is using the Normal function to produce the required series. 


 @Risk

  Exchange_rate

 

Here is a screenshot of the model:

 

 

Column C of the above model shows the value of sigma for each period, taking the value of 0.05 for the periods 1 to 99. For the following periods sigma will take values 0.05, 0.08 or 0.04 depending on the party that wins the election. The simulation of the election is shown in cell H17, which uses a RiskDiscrete function with values 1 (Conservative), 2 (Labour) and 3 (Liberal Democrats), and probabilities of success 25%, 70%, 5% respectively. Cell H18 looks up the value of sigma for the party that has won the election, which is then fed into column C.

 

Cell I19 shows the period of change in the exchange rate volatility if the Conservative party wins the election. In addition, cell G25 checks if the Conservative party has won the election, and if it has, then returns either 1 or 0 with 50% probability each. Finally, the output column D is using the RiskNormal function to produce the required series.


IMPORTANT: Loading a spreadsheet in Excel will not load the simulation software packages such as Crystal ball or @RISK. If the simulation software package is not running while you are loading a spreadsheet, you will need to load it manually. For your convenience, you are advised not to shut down Excel and the simulation software package that works with it when you finish studying a particular model, but keep them minimized in case you want to look at another model.

Quizzes

Our quizzes provide an interactive approach to finding out how much knowledge and understanding of the material you have reached. All quizzes contain several questions, and after answering each question, you will be able to see the correct answer with explanations.

Process flow diagrams

The flow diagrams provide a visual way to represent connections between several processes or stages. Colored boxes represent a process or an event, while the arrows represent a flow, either the normal path or an alternative possible path. You can click on most of the colored boxes and on some of the arrows to be taken to a topic where this process and event is explained.  Below is an example of a process flow diagram for Determining a prior distribution for a single parameter estimate:

Prior dsit. for single par.estimate


Improving ModelAssist

If you have suggestions for extra topics for ModelAssist, or suggestions on how the content could be improved, please don't hesitate to contact us – we would be very happy to hear from you.

 

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