This campaign argues that any model that is used to inform policy should be made public in all its detail (including full documentation and source code), so that other researchers can:

• download the full documentation
• download the source code with sufficient instructions to run and inspect it
• be able to change the code and run their own experiments with it
• critique it and suggest improvements
• extend the model and release this for others to check
• examine the assumptions it encodes
• verify and comment upon any policy interpretation its results have been subject to

The principle is this. If politicians make decisions they are responsible for this. If they make it partially or wholly informed by a complex model, they can not fully understand the basis on which they are making these decisions. Thus the public have a right to know that other experts can inspect and check such a model. The more complex a model, the more influence it has on policy and the greater the impact such policy has on people’s lives, the more vital this is.

Open, transparent modelling is part of an open society, when it deals with phenomena that are so complex that their management requires modelling.

For more details see the full Manifesto.