RATES, RATIOS, AND VITAL STATISTICS

• Ratio is also called a proportion of the quotient of the sum of two numbers, like the number of deaths per population
• Rate is a ratio involving a time count or measurement observed over a period and then divided by its base or population of observation
• Incidence Rate measures the frequency of occurrence of a phenomenon during a given period of time and deals only with new cases
• Prevalence rate measures the proportion of the population that exhibits a particular disease at a particular time, dealing with total (old and new) number of cases
• Incidence, also known as attack rate, refers to newly discovered cases of a particular disease, used for acute conditions and accidents
• Prevalence refers to newly discovered and old cases of a particular disease over a population, used for chronic conditions and disabilities
• Crude Birth Rate (CBR) is a measure of the fertility of the population, expressed in population units of 1000
• Crude Death Rate (CDR) is a measure of the risk of dying from all causes in a population
• Maternal Mortality Rate (MMR) measures the risk of dying due to the process of pregnancy, childbirth, and puerperium
• Infant Mortality Rate (IMR) measures the risk of dying under 1 year of age, calculated as deaths under 1 year of age divided by the number of live births, multiplied by 1000
• Fetal Death Rate measures the risk of dying before birth
• Peri-Natal Mortality Rate measures the loss of life in later pregnancy and early infancy, around the period of birth (a month or more before births and one month after birth)