Читать книгу Medical Statistics - David Machin - Страница 115

1 What is the population from which the sample was taken? Are there any possible sources of bias that may affect the estimates of the population parameters?

2 Have reference ranges been calculated on a random sample of healthy volunteers? If not, how does this affect your interpretation? Is there any good reason why a random sample was not taken?

3 For any continuous variable, are the variables correctly assumed to have a Normal distribution? If not, how do the investigators take account of this?