Proportion: is the fraction of the population is affected by a disease. Proportionate mortality is a commonly used proportion in epidemiology and provides the proportions of death that is caused by a specific disease. For example 30% of deaths in canada in 2004 were caused by cancer. = number of deaths attributed to a disease in a population during a specified year x 100. Number of deaths in the same population and year. Rates: tell us how fast the disease is occurring in a population. So, there is a time period that must be considered. The time period is arbitrary i. e. month, year(s). Some examples of rates include; crude mortality, incidence and prevalence rates. The occurrence of illness or diseases and is calculated with the population at risk or person-time, if people at risk is observed for different period of times. Incidence and prevalence are the two measures of morbidity.