Just because it's not reported in the Times, doesn't mean it doesn't happen. It actually can happen quite frequently. Trial protocols can pre-specify early sto

Just because it's not reported in the Times, doesn't mean it doesn't happen. It actually can happen quite frequently. Trial protocols can pre-specify early stopping criteria: if we see drug A is better than drug B by a factor of X at time T, then we can declare superiority with given statistical confidence.