rate (rat)

1. A record of the measurement of an event or process in terms of its relation to some fixed standard; measurement is expressed as the ratio of one quantity to another (e.g., velocity, distance per unit time). 2. A measure of the frequency of an event in a defined population; the components of a r. are: the numerator (number of events); the denominator (population at risk of experiencing the event); the specified time in which the events occur; and usually a multiplier, a power of 10, which makes it possible to express the rate as a whole number rather than an awkward decimal. [L. ratum, a reckoning (see ratio)]
abortion r. the number of abortions per 1000 terminated pregnancies during a given period of time.
age-specific r. a r. for a specified age group, in which the numerator and denominator refer to the same age group.
attack r. a cumulative incidence rate used for particular groups observed for limited periods under special circumstances, such as during an epidemic.
average flow r. the flow r. determined by dividing the total volume of urine passed by the time of voiding.
basal metabolic r. (BMR) basal metabolism
baseline fetal heart r. the average heart r. for a particular fetus during the diastolic phase of uterine contractions.
birth r. a summary r. based on the number of live births in a population over a given period, usually one year; the numerator is the number of live births, the denominator is the midyear population.
case fatality r. the proportion of individuals contracting a disease that die of that disease.
concordance r. the proportion of a random sample of pairs that are concordant for a trait of interest. A high r. of concordance may be generated in several ways, many of which may result from irrelevant bias; but broadly it is taken as evidence of causal connection (e.g., in the case of identical twins, a genetic component or in spouses of assortative mating).
critical r. a heart r. at which aberration or incomplete block will occur; a result of shortening of cycle length so that it barely includes the refractory period.
death r. an estimate of the proportion of the population that dies during a specified period, usually a year; the numerator is the number of people dying, the denominator is the number in the population, usually an estimate of the number at the mid-period.crude death rate, mortality r;
erythrocyte sedimentation r. (ESR) the rate of settling of red blood cells in anticoagulated blood; increased r.'s are often associated with anemia or inflammatory states.
fatality r. the death r. observed in a designated series of persons affected by a simultaneous event such as a disaster.
fetal death r. the number of fetal deaths divided by the sum of live births and fetal deaths occurring in the same population during the same time period.stillbirth r;
fetal heart r. in the fetus, the number of heart beats per minute, normally 120 to 160.
five year survival r. the proportion of patients still alive five years after a diagnosis or form of treatment is completed. Usually applied to statistics of survival of cancer patients, since after five years, recurrences are much less likely to occur.
general fertility r. a refined measure of fertility in a population; the numerator is the number of live births in a year, the denominator is the number of females of child-bearing age, usually defined as ages 15-44 (but increasingly recognized as extending to age 49).
glomerular filtration r. (GFR) the volume of water filtered out of the plasma through glomerular capillary walls into Bowman's capsules per unit time; it is considered to be equivalent to inulin clearance.
gross reproduction r. the average number of female children a woman would have if she survived to the end of her childbearing years and if, throughout that period, she were subject to a given set of age-specific fertility r.'s and a given sex ratio at birth; this r. provides a measure of the replacement fertility of a population in the absence of mortality.
growth r. absolute or relative growth increase, expressed per unit of time.
growth r. of population a measure of population change in the absence of migration, comprising addition of newborns and subtraction of deaths; the result is known as the natural r. of increase of the population; it is the difference between the crude birth r. and the crude death r.
hazard r. theoretical measure of the risk of occurrence of an event, e.g., death, new disease, at a point in time.
heart r. r. of the heart's beat, recorded as the number of beats per minute.
inception r. the r. at which new spells of illness or cases of a condition occur in a population.
incidence r. the r. at which new events occur in a population. The numerator is the number of new events occurring in a defined period; the denominator is the population at risk of experiencing the event during this period.
infant mortality r. a measure of the r. of deaths of liveborn infants before their first birthday; the numerator is the number of infants under one year of age born alive in a defined region during a calendar year who die before they are one year old; the denominator is the total number of live births; often quoted as a useful indicator of the level of health in a community.
initial r. initial velocity
lethality r. mortality r
maternal death r. the number of maternal deaths that occur as the direct result of the reproductive process per 100,000 live births. See rate. See also maternal death.
mitotic r. the proportion of cells in a tissue that are undergoing mitosis, expressed as a mitotic index or, roughly, as the number of cells in mitosis in each microscopic high-power field in tissue sections.
morbidity r. the proportion of patients with a particular disease during a given year per given unit of population.
mortality r. death rlethality r., mortality (2);
mutation r. the probability (or proportion) of progeny genes with a particular component of the genome not present in either biological parent; usually expressed as the number of mutants per generation occurring at one gene or locus.
neonatal mortality r. the number of deaths in the first 28 days of life divided by the number of live births occurring in the same population during the same period of time.
peak flow r. maximum urinary flow r. during voiding as measured by a uroflowmeter.
perinatal mortality r. the number of stillborn infants of 24 completed weeks or more plus the number of deaths occurring under 7 days of life divided by the number of stillborn infants of 24 weeks or more gestation plus all liveborn infants in the same population, regardless of the period of gestation.
pulse r. r. of the pulse as observed in an artery; recorded as beats per minute.
recurrence r. in genetic counseling, the risk that a future offspring will be affected given some specific set of relatives of whom at least one is already affected.
repetition r. the number of pulses per minute, describing an energy outpute.g., ultrasound pulses in echocardiography rather than vascular pulses.
respiration r. frequency of breathing, recorded as the number of breaths per minute.
sedimentation r. the sinking velocity of blood cells, i.e., the degree of rapidity with which the red cells sink in a mass of drawn blood.
shear r. the change in velocity of parallel planes in a flowing fluid separated by unit distance; its units expressed in seconds-1.
slew r. in electronic pacemaker function, the maximum rate of change of an amplifier output voltage; important variable affecting heart function as controlled by an electronic pacemaker. Sensing circuits in the pacemaker often respond to the slew r. rather than to the absolute amplitude of the voltage pulse.
steady-state r. steady-state velocity
steroid metabolic clearance r. (MCR) a measure of the r. of metabolism of a given steroid within the body, usually expressed as liters of body fluid that contain the amount of steroid metabolized per day.
steroid production r. the total quantity of a given steroid formed in the body, usually expressed as milligrams per day; represents the sum of the glandular secretion of the steroid and extraglandular formation of it from various steroid precursors.
steroid secretory r. the r. of glandular secretion of a given steroid, usually expressed as milligrams per day; does not include any amount of the steroid that might be formed extraglandularly.
stillbirth r. fetal death r
voiding flow r. urinary flow as a function of time during micturition, as graphically recorded by a flow meter.


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