Simulating data

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The simulator offers a visualisation of a mark-recapture experiment and produces data that can then be used to test the applicability of the various methods of analysis. You will begin to realise that a large proportion of the population must be marked for accurate population estimates to be obtained. The simulator works by setting in motion a known number of 'animals' and tagging those that enter traps. The motion of the animals, random or otherwise, can be selected.

Once the simulation is completed the data set produced can be viewed from the Full Data, Open Summary and Closed Summary tabs and is available to all of the methods.

 

To start the simulator select Planning: Simulate from the drop-down menus at the top of the program.

 

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You will be presented in a blank area within which the simulation will be displayed. Click on the blue triangle Run button and the Simulation Setup window will be displayed.

 

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simulation parameters

 

This window will allow you to select a variety of options for producing different types of simulation. The options available and their purpose are described below. At the bottom of the Simulation Setup window there are Help, Cancel and Run buttons. To undertake a simulation, click on the Run button.

 

Simulation options do not need to be set, as the program will use reasonably sensible default values.

 

When a simulation is run you will be able to watch the data set being created. The traps appear as grey or black squares. They are only actively trapping when they change to black. The time when they are grey is used to give the 'animals' time to mix and disperse. The 'animals' are presented by small 'butterfly' icons.  At the end of the simulation, or at any other time if you can catch them with the mouse, a click on one of the animals will present a colour coded history of its capture history along the left hand edge of the screen.

 

At the bottom of the screen are some summary statistics that will keep you informed of progress. Tagging No. gives the number of sampling occasions undertaken. No. Alive is the number of 'animals' currently alive in the simulation, No. Born gives the number of new arrivals which could either arise by birth or immigration, and No. Died gives the number lost either by death or emigration.

 

Setting simulation parameters