Precisely how you manage data depends on the data available and your purpose. However, there are two techniques that have proven very useful.
The first technique is the simplest. Put all data equations for exogenous drivers in one group in a model and use only raw data for comparison. This works fine unless you need to manipulate the raw data before comparing it to model results.
The second technique is to build a separate data model. This is useful if the model must manipulate a lot of raw data. In this way, you can keep the names of the data series the same as the names of the model variables. This is not possible inside of a single model. (We made this design choice to avoid the confusion arising from a single model having a data series and a variable with the same name. While Vensim might be able to keep track of this, trying to distinguish what was actually on the right side of an equation from what was intended to be on the right side would be confusing for users.)== F_25} Such a "data" model contains only := equations. Vensim simulates the model using the raw data as input. The resulting data set (.vdf) file contains both the raw and the manipulated data. The "real" model uses this output data set for simulations and never directly refers to the raw data.
