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.

Accrual in clinical trials is difficult to predict - and funders want to make sure you've taken a robust approach. Less than one third of publicly funded trials managed to recruit according to their original plan often resulting in request for additional funding and/or time extensions.

The Conditional model described by Barnard et al represents a reasonable approach to this problem for multi centre clinical trials.

The models used in Recruitment Modeller are deterministic - that is they produce the same answer every time. They are also - obviously - only as good as 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.