Translations:Advanced Field Epi:Manual 1 - Disease Investigation/307/en
Some risk factors do not change over time (breed, species and often sex) and may be described as fixed (unchanging). Other risk factors (age, body weight, feed, location, recent treatments) may change over time and may be measured at a defined time or used to develop categories (age less than 1 year or greater than 1 year) or averages.