The Wiki pages here provide a repository for Analytica models and libraries. Supplementary material may be included here describing the model, its usage, etc. Models or libraries may be contributed because they are useful for particular applications, provide a starting point for certain modeling tasks, demonstrate an Analytica concept, etc.

Several dozen models are included with the Analytica distribution, installed onto your machine when you install Analytica. These models are not also here on the Wiki yet, but may be added in the future. Furthermore, as updates to these models occur, more recent versions will be made available here.

Analytica users may also contribute their own models and examples here. For instructions on how to upload your own contributions, see Uploading Example Models.

Grant Exclusion Model

Grant Exclusion

This model tests a hypothesis about the distribution of an attribute of the marginal rejectee of a grant program, given the relevance of that attribute to award of the grant. It could be used by an organization to make decisions as to whether to fiscally-sponsor another organization that will use that fiscal sponsorship to apply for grants, by looking at the effect on the pool of grant recipients overall.

Donor/Presenter Dashboard

Donor-Presenter Dashboard

This model implements a continuous-time Markov chain in Analytica's discrete-time dynamic simulation environment. It supports immigration to, and emigration from, every node.

It can be used by an arts organization to probabilistically forecast future audience evolution, in both the short and the long (steady state) term. It also allows for uncertainty in the input parameters.

Project Planner

Download: Project Priorities 5 0.ana

A demo model that shows how to:

Evaluate a set of R&D projects, including uncertain R&D costs, and uncertain revenues if it leads to release of a commercial product.
Use multiattribute analysis to compare projects, including a hard attribute -- expected net present value -- and soft attributes -- strategic fit, staff development, and public good will.
Compare cost, NPV, and multiattribute value for a selected portfolio of projects.
Generate the best portfolio (ratio of NPV or multiattribute merit to cost) given a R&D budget.

This link is only a test, and to an older version: <link target="blank">http://lumina.com/wiki/images/4/43/Project_priorities_2007_4.0.ANA</link>

California Power Plants

A model that demonstrates the use of choice pulldowns in edit tables. The model is created during a mini-tutorial on Inserting_Choice_Controls_in_Edit_Table_Cells elsewhere on this Wiki.

Media:California_Power_Plants.ANA

Dependency Tracker Module

This module tracks dependencies through your model, updating the visual appearance of nodes so that you can quickly visualize the paths by which one variable influences another. You can also use it to provide a visual indication of which nodes are downstream (or upstream) from an indicated variable.

The module contains button scripts that change the bevel appearance of nodes in your model. To see how Variable X influences Variable Y, the script will bevel the nodes for all variables that are influenced by X and influence Y. Alternatively, you can bevel all nodes that are influenced by X, or you can bevel all nodes that influence Y.

In the image above, the path from dp_ex_2 through dp_ex_4 has been highlight using the bevel style of the nodes. (The result of pressing the "Bevel all from Ancestor to Descendant" button)

Dependency_Tracker.ana

Total Allowable Harvest

The problem applies to any population of fish or animal whose dynamics are poorly known but can be summarized in a simple model:

N_t+1 = N_t*Lambda - landed catch*(1+loss rate)

where N_t is the population size (number of individuals) at time t, N_t+1 is the population size at time t+1, Lambda is the intrinsic rate of increase and the loss rate is the percentage of fish or animals killed but not retrieved relative to the landed catch, or catch secured.

The question here is to determine how many fish or animals can be caught (landed) annually so that the probability of the population declining X% in Y years (decline threshold) is less than Z% (risk tolerance).

Two models are available for download. One uses the Optimizer (NlpDefine) to find the maximum landed catch at the risk tolerance level for the given decline threshold. The other (for those using a version of Analytica without Optimizer) uses StepInterp in an iterative way to get that maximum landed catch.

Models contributed by Pierre Richard

Earthquake Expenses

An example of risk analysis with time-dependence and costs shifted over time.

Certain organizations (insurance companies, large companies, governments) incur expenses following earthquakes. This simplified demo model can be used to answer questions such as:

What is the probability of more than one quake in a specific 10 year period.
What is the probability that in my time window my costs exceed $X?

Assumptions in this model:

Earthquakes are Poisson events with mean rate of once every 10 years.
Damage caused by such quake is lognormally distributed, with mean $10M adn stddev of $6M.
Cost of damage gets incurred over the period of a year from the date of the quake as equipment is replaced and buildings are repaired over time: 20% in 1st quarter after quake, 50% in 2nd quarter, 20% in 3rd quarter, 10% in 4th quarter.

Model file: Earthquake expenses.ana

Regulation of Photosynthesis

Author Lonnie Chrisman, Ph.D.

A model of how photosynthesis is regulated inside a cyanobacteria. As light exposure varies over time (and you can experiment with various light intensity waveforms), it simulates the concentration levels of key transport molecules along the chain, through the PSII complex, plasto-quinone pool, PSI complex, down to metabolic oxidation. The dynamic response to light levels, or changes in light levels, over time becomes evident, and the impact of changes to metabolic demand can also be observed. In the graph of fluorescence above, we can see an indicator of how much energy is being absorbed, in three different cases (different light intensities). In the two higher intensity cases, photoinhibition is observed -- a protective mechanism of the cell that engages when more energy is coming in than can be utilized by the cell. Excess incoming energy, in the absense of photoinhibition, causes damage, particularly to the PSII complex.

This model uses node shapes for a different purpose than is normally seen in decision analysis models. In this model, ovals, instead of depicting chance variables, depict chemical reactions, where the value depicts the reaction rate, and rounded rectangles depict chemical concentrations.

Two models are attached. The first is a bit cleaner, and focused on the core transport chain. The second is less developed, but is focused more on genetic regulation processes.

Photosynthesis Regulation.ana - main regulation pathways
Photosystem.ana - rough sketch of genetic regulation.