english: For example, if the cohort in our herbal study consisted of people who took the supplement for health reasons, they may have already had higher rates of nausea than the other people in the sample.
non_english: Na primer, ako se kohort u našoj studiji sa lekovitim biljem sastoji od ljudi koji uzimaju suplement zbog zdravstvenih razloga, oni možda već imaju višu stopu mučnine od drugih ljudi u uzorku.