Mortality data are derived from death certificates completed by physicians, which are collected by the Office of the Registrar General (ORG). The cause of death reported is the occurrence that starts the sequence of events leading to death.
Consequently, there may be some uncertainty in classifying deaths when there are multiple causes. Determining true cause of death may be influenced by the social or legal conditions surrounding the death and by the level of medical investigation, e.g. AIDS and suicide.
Data are analyzed by the residence of the deceased, not where the death occurred. Records for Ontario residents who die outside of the province are not available and are therefore excluded. Otherwise, due to legal reporting requirements, registration of deaths is considered to be virtually complete.