Does it matter if people have been missed from the list of participants?
It was not necessary to include all test participants in the study, though it was desirable that as many as possible of them were included, as the ability of the study to detect any harmful effect of test participation would be larger the larger the population studied. It was, however, essential that men were selected for inclusion in the study in an unbiased way. That is, that they were representative of the whole group of test participants in terms of their subsequent health, and were not selected in such a way as to over or under represent those who have subsequently suffered ill-health or died.
