a lot. It will make the experiment much simpler to avoid the bias. But it is a tougher test because it is either no symptom or there is (even slightly). I think the percentage of success will be reduced upon this measure. Nevertheless, the change in scores will still be used as the secondary, perhaps together with QoL.

If it cannot be defined as preventive treatment, can the occurrence be still used as a measure?

Thank you very much for your very helpful thoughts.

Are you a longtime XYSer?