Recruitment Modeller
It's all about filling the bucket.
Recruitment Modeller is a tool to predict recruitment to multi-centre clinical trials. The predictions are based on the unconditional and conditional models as described in Barnard et al, BMC Medical Research Methodology 2010, 10:63.
The models used in Recruitment Modeller are deterministic - that is they produce the same answer every time. They are also - obviously - only as good at the parameters they are given. It's well known that trials tend to over predict their ability to recruit. You'll only get a good prediction from Recruitment Modeller if you give it good data.
What a modelling tool like this does facilitate, however, is rapid sensitivity analysis. You can quickly change the parameters of a trial to see what happens to the prediction.