Plans to impose effort-reporting on scientists, as mentioned in your Editorial 'On the paper trail' and News story 'Researchers criticized for poor time-keeping' (Nature 449, 508 and

512–513; 2007), will be difficult to implement. In practice, it is almost impossible to give an accurate estimate of effort, because scientists are rarely off the job, even when asleep. If

they are not actually doing a particular task, they are planning the next, or puzzling over the most recent observation. How should that time be counted? In most research, the edges of a

project are only known indistinctly. So in many cases it is difficult to know when one has wandered from one project to another or into an unfunded area.