One of the first steps in conceptualizing a model is to determine what time frame the behavior occurs over. If you are looking at the flow of patients in a clinic, you may want to look at behavior over the course of a day and measure time in hours or minutes. If you are looking at technology change, on the other hand, you may want to consider behavior over a century and measure time in years. Often, sketching a graph on a piece of paper and then labeling the x-axis is a good way to select both the units of measure and start and stop time.
Setting the basic time bounds, including units of measure, start, stop and DT is done from the Model Settings Properties Panel. This tells the software how to run the model and graphs and tables you create will use these settings for display.
When you specify the start and stop time they are simply numbers. For example, the model might run from 0 to 60 in months, or 2000 to 2050 in years. In many cases it is useful to display time in a different format. For example, on the model running for 60 months, we might want to associate that with the beginning of 2015 through the beginning of 2020. This can be done using time labels.
To set up time labels go to the he Model Settings Properties Panel and click on the Time Labels button, this will open the Manage Time Labels dialog box. You can create a number of different time labels (each named), though often simply changing the format for default time label will suffice.
The default time label is an adaptive number that displays decimal places based on all of the numbers to be displayed in a graph or table. For example, if the value 2.5 is to be shown as a time label, then 0.0 instead of just 0 will be used. This adaptive approach gives very good results in general, but you can also provide specific precisions just as you can for variables.
In addition to numbers, you can specify date style sequences of values for years, quarters, months, weeks and days. This is done by recasting the underlying time value as specified in the run specifications to work in this form. For details see the Set Time Label Format dialog box.
When you create a new graph or table it will use the Time Label you have indicated to be the default. You can change this by right clicking (Ctrl-clicking) and selecting Format>Time and then the name of the Time Label you would like to use. Changes to that Time Label will change the appearance of the graph or table.